That's an odd question!

It's common knowledge that the 4-year cycle is created by the halving event that happens every 210,000 blocks.
That's about 2,100,000 minutes or 3.995 years given 10 minute blocks (and not counting leap years).
It's assumed that less selling pressure from miners creates the cycle.

21M 21M 21M

You've been in crypto so long there's a better chance you're trolling me right now than asking a legitimate question.
But I'll give you the benefit of the doubt.
Pretty wild!