You never know how long they’re going to be able to prop up the scams. Additionally, many of the big exchanges, being unregulated, are alleged to (either directly, or through large players they’re associated with) manipulate the market and trade against customers. Front running, etc.

Put up a large short position, and soon enough there will be a pump and dump to liquidate it. And if you do make money, have you noticed that these exchanges often go down for “maintenance” when big price movements are happening? There’s no guarantee you’ll be able to close out a position when you need to.

The only way to win is not to play.

Not buying and keeping your currency elsewhere may just be a totally reasonable alternative.

I have been consistently wrong about when various scams have exploded, both thinking that they would explode earlier than they did and that it would take longer. If I'd tried to short the crypto crashes so far I probably would have lost money overall even with just the ones where I was correct about them going to zero.

With a lot more research I perhaps could be net positive, but I don't actually want to spend a lot more time digging into something that I consider stupid bullshit.

I could take bets on the next mass shooting, too, but I prefer not to make money off of some things that I can nonetheless statistically foresee.

The market can stay irrational longer than you can stay solvent.