If Bitcoin were to crash, you wouldn't be able to exit. The exchanges would be overloaded, the price would collapse while you[1] can't trade, and you may also discover that some of the exchanges have stolen your money because they are insolvent.

[1] Although some whale customers may be able to. They may win big - or at least, lose less, at your expense.

Between now and the event horizon, there may be considerable opportunity.

I mined some bitcoin in the early days, when you could solo-mine for a week or so and net coins. I had a handful of coins that I cashed out for less than $100, because I didn't like Bitcoin as a long-term investment. If I'd sold half, I'd have made a tidy profit off the sale of the first half, with another handful of coins that, even if they tanked, I'm still in the black. But, if they go to some ridiculous number, like $10,000, I'm substantially better off.

Needless to say, I didn't save half, but even for people buying in now (I'm not), could end up doing well, even if the trajectory of BTC is $15k, $20k, $45k, $0, Of course, if the trajectory is $15k, $10k, $5k, $0, they'll be shit out of luck.

Exactly this. During the subprime crisis, even the big banks couldn't offload their risk.

It's crazy to think an amateur investor in Bitcoin is going to be able to "keep the exits clear". By the time you see the downturn those exits are long gone.

Banks and large investors need to offload billions of dollars worth of assets. Orders of magnitude more than what the average amateur will generally be working with.

If an amateur can actually guess when the downturn starts (a really big if), they should not have much of a problem exiting. Even if a large investor can identify the downturn, if they try to exit quickly, they will probably just exacerbate the problem, without even being able to get all the way out themselves

Yeah, but now you're trying to time the market. That's... a less than optimal strategy.

Of course, you need to rely on luck in a bubble. There's never any guaranteed returns in anything with a possibility of a high return.