The pattern of Bitcoin's four-year bull-bear cycles, why has it never been broken?

In October 2025, Bitcoin once again hit a new all-time high of $126k. At this moment, just over 18 months after the fourth halving in April 2024. This is no coincidence—after the 2017 top, 18 months post-halving; after the 2021 top, also 18 months post-halving. When we look back at Bitcoin's history, a shocking fact stands before us: from the first halving in 2012 to today, thirteen years have passed, and this “four-year cycle” pattern has never been broken.

01. A thirteen-year-long “coincidence”

Bitcoin was born in 2009, and the first bull market that truly caught the market’s attention appeared in 2013. At that time, in November 2012, Bitcoin completed its first halving, reducing the block reward from 50 to 25 coins. A year later, the price skyrocketed from teens to $1,200. Many thought this was just a fleeting speculative bubble.

Then, in July 2016, the second halving occurred. In the following 2017, Bitcoin soared from over $400 to nearly $20k, with the entire cycle seeing an 80 to 90-fold increase. The market began to notice the word “halving,” but most still regarded it as coincidence.

In May 2020, the third halving took place, and in 2021, Bitcoin reached $69k. Three halving events, three bull markets. After each halving, the top was reached within 12 to 18 months, followed by a 70% to 85% crash, then about a year of bear market bottoming out, and everything started over. This rhythm is as precise as a mechanical clock.

By 2025, after the fourth halving in April 2024, Bitcoin hit a new high of $126k on October 6, 2025. 18 months—completely consistent with the previous two cycles. Those predicting “this time is different” have once again been proven wrong.

Thirteen years of data do not lie: although the gains after halving have decreased each time—nearly 9,000% the first time, about 2,800% the second, and around 700% the third—the existence of a bull market has never been absent. This is not superstition like “fishing with a carved boat,” but a structural pattern repeatedly validated by market behavior. Patterns can be questioned, but facts cannot be erased.

02. Why four years? Mysticism?

Many ask: if the four-year cycle is just a coincidence, why does it perfectly coincide with the halving time?

The answer lies in Bitcoin’s underlying code. When Satoshi Nakamoto designed Bitcoin, he set a strict rule: every time 210k blocks are mined—roughly four years—the mining reward halves. This is not a marketing gimmick made on a whim, but a deliberately embedded monetary issuance mechanism aimed at countering the endless inflation of traditional fiat currencies.

How does this mechanism drive prices? The core logic is two words: supply and demand.

If demand remains unchanged, the daily new supply of Bitcoin drops sharply from 900 coins to 450 coins, directly reducing the selling pressure the market needs to absorb. Since Bitcoin’s total supply is capped at 21 million coins, most of which are already locked by long-term holders, the circulating supply in the market is almost only the new coins produced daily by miners. When this new supply suddenly halves, and demand does not decrease proportionally, upward price pressure becomes irreversible.

This is the simplest economic principle, yet it is often overly complicated by many.

Of course, relying solely on the supply shock from halving cannot explain the entire magnitude of each bull run. The ICO frenzy in 2017, institutional entry and DeFi Summer in 2021 all acted as demand amplifiers in their respective cycles. But it’s worth noting that each halving occurs at the bottom of a bear market—Bitcoin fell from $1,200 to $164 in 2015, then halving came; from $20k to $3,000 in 2018, then halving; from $69k to $15k in 2022, then halving again.

Is this just coincidence? I prefer to believe it’s an intrinsic self-healing mechanism built into Bitcoin as a “digital life form.” It reignites scarcity at the most desperate bear market moments, planting the seeds for the next bull run.

03. Human nature never changes

Supply and demand are fundamental, but they are far from the whole story.

If the four-year cycle of Bitcoin were just a simple economic model, it would have been eliminated by arbitrageurs long ago. What truly sustains this thirteen-year pattern is a more fundamental factor—human nature.

In every bull market, we hear almost identical stories:

- “This time is different, institutions are in, it’s a perpetual bull market.”
- “Bitcoin is now mainstream, there won’t be 80% crashes anymore.”
- “Halving is fully priced in, no excess returns.”

These voices appeared in 2013, 2017, 2021, and 2025. Yet each time, the market teaches everyone a brutal lesson: markets can change, but human nature does not.

The 2025 bull market is especially ironic. Early 2024, Bitcoin spot ETFs were approved in the US, with giants like BlackRock and Fidelity rushing in, institutional holdings reaching record highs. For a time, the market was filled with optimistic narratives of “eternal bull markets”—institutions are smart money, they won’t chase prices like retail investors, Bitcoin’s volatility will diminish, and cycles will disappear.

However, after reaching $126k in October 2025, Bitcoin plummeted about 25% within less than a month, briefly falling below $90k. Market sentiment shifted from euphoria to panic, eerily similar to the top structures of 2017 and 2021. Those who believed “this time is different” were once again taught a harsh lesson.

04. Why does this happen?

Because regardless of whether market participants are retail or institutional, the core driver of trading has never been “rationality,” but greed and fear. Institutions are not gods—they also face redemption pressures and risk controls. When driven by greed to leverage and build positions, their behavior is no different in essence from retail investors.

Conversely, the most desperate moments of each bear market are precisely when halving is about to occur. In 2015, Bitcoin fell from $1,200 to $164, and the market said “Bitcoin is dead,” then in 2016, halving happened, and the bull market began. In 2019-2020, Bitcoin hovered around $3,000–$4,000, and the market said “no more bull markets,” then in 2020, halving occurred, and the bull resumed in 2021. In 2022, the bear market bottomed at $15k, and the market again declared Bitcoin dead, but in 2024, halving happened, and in 2025, new highs were made again.

When you think “this time is really over,” the cycle is actually brewing the next starting point.

05. The cycle is still there, just in a different form

Entering 2026, discussions about whether the “four-year cycle” has failed are heating up again. Some point out that this bull market’s gains are only 7 to 8 times, far less than the nearly 20 times in 2017; altcoins are sluggish, Bitcoin’s market dominance remains close to 59%; market sentiment is cold, lacking the previous全民狂欢. Many analysts believe that with institutional dominance, the four-year cycle is being broken.

These observations are not entirely unreasonable. The 2024-2025 bull market is indeed different: more moderate gains, less volatility, and a lack of frenzy. But I tend to believe that the cycle has not been broken; it has been “suppressed” and “prolonged.”

Continuous buying from ETFs provides the market with a “liquidity cushion,” reducing the depth of crashes. Miners are no longer forced to sell large amounts like before; they now hedge risks with derivatives, and in 2025, there was even a rare phenomenon of miner addresses increasing in balance. The 2022 bear market’s decline of only 77% was less than 86% in 2014 and 84% in 2018—crashes are shallower, surges are slower, but the outline of the cycle remains clear.

The cycle has not been eliminated; it has only changed its form. Just like teenagers grow taller and voice change during puberty, but the human lifecycle does not disappear. Bitcoin’s “maturity” makes its volatility more refined, but it does not alter its origin in code, its dependence on supply and demand, or its fundamental human nature.

06. Patterns are never meant for precise prediction

Writing this, I recall an interesting phenomenon: in the crypto world, those who truly make money are never the clever people who frequently predict “how high this time,” but the “fools” who quietly dollar-cost average during the bleakest bear markets and quietly exit during the craziest bull markets.

They do not predict; they follow.

Bitcoin’s four-year cycle pattern is never meant for “carving a boat to seek the sword” to precisely predict tops and bottoms, but as a reminder to “do the right thing at the right time.” It tells us: when you think Bitcoin is finished, it might be the best time; when you think Bitcoin can go to the moon, it’s probably time to be cautious.

In 2028, the fifth halving will arrive. By then, the block reward will drop to 1.5625 coins, and the daily new supply will further decrease to around 225 coins. Looking back from today, perhaps this pattern will be questioned, ridiculed, or even declared “failed.” But if you ask me whether it will be broken?

My answer is: Bitcoin’s code is still running, human nature has not evolved. The four-year cycle will most likely continue as scheduled. By then, people will start a new round of “this time is different” debates. And the cycle will only continue to quietly operate—like a clock that never speaks but has never been wrong.