Four-Year Halving: Every 210,000 blocks produced, approximately every four years, the Bitcoin reward is halved, from an initial 50 coins, after three halvings it is now 6.25 coins, ensuring scarcity.

Bull Market Starts Six Months After Halving: Halving reduces the inflation rate while increasing demand, attracting new funds, and the imbalance of supply and demand drives prices up. For example, after the halving in July 2016, a bull market began by the end of the year.

Bull Market Ends One and a Half Years After Halving: During this stage, there are many profits taken, selling pressure exceeds buying pressure, valuations are high, and even a slight disturbance can trigger large-scale sell-offs, ending the bull market.

Crash Year with 80% Drop to the Bottom: Prices plummet for about a year, with a drop of 80%. During this time, panic spreads, and when prices fall below their value, bottom-fishing capital enters the market, as in 2018. The correlation between the Bitcoin bull market and altcoins.

After a period of Bitcoin bull market, investors seeking higher returns shift their funds to altcoins, increasing their trading volume and driving prices up. However, this is contingent on Bitcoin being in a bull market; otherwise, altcoins lack upward momentum, as Bitcoin dominates market sentiment and capital flow. Summarize the iron law mentioned in the article into one sentence: What is the reason for the bull market starting after halving? What factors will affect Bitcoin's market performance after halving?