Tether collapse is still the big one.

Yeah, that's my theory too on one reason it hasn't fully crashed (meaning "the world running out of greater fools"). Unlike tulip bulbs or the dot.com crash, bitcoin is a world-wide phenomenon so there is large supply of bitcoin buyers. Yeah, even the dot.com crash was done in the highly regulated US stock market.

Also thinking, since it's extremely difficult to regulate, was wondering if some very clever people with huge holdings have formed a cartel and are doing a lot of price manipulation to prevent it from fully collapsing (maybe even during a rise in price, causing it to drop early to prevent a major run up). But that's just a theory.