What's stopping crypto from going to 0?

I'm somewhat clueless on crypto. Clearly there are a lot of people making money from it, but there doesn't seem to be any value added in the process of buying and selling it(or even worse value lost through fees). So the only source of income to those profiting is from others losing in some way?

It seems to me that there are lots of people who feel like they are profiting because they've got a certain amount of crypto in their account which has value in the marketplace at present. If for some reason there was a mass sale the price would plummet and those who sold earlier would profit from those who didn't.

Is there a flaw in my thought process?