It is never okay to generalize. There are good exchangers still, you just have to find the best one. Also, given that the issue is still recent, for sure exchangers would take extra caution with their action 'coz they might be tangled with FTX's case instead. Try to calm down, although what happened is unfortunate, it would be worse if you',d be worried that much. If it is really draining on your end, try to pull out your investments for now. Being worried is just fine, but everything that is too much would be bad for sure.
I feel like its not about security but the type of person the owner is. If there is an exchange out there which users put their funds in, and the exchange ends up using the user funds to buy a whole company to make bigger profit, that exchange will eventually crash, there is no way back.
What FTX imagined was they would make enough profit from the companies they bought with user funds to pay the users back, and it would allow them to grow bigger because users would keep on investing and it would be sort of like semi-ponzi because the deposits will cover the withdrawals, they had of course some saved aside as well. But we all know market crashed so they did terribly for sure.
If the owners have a bad intention right from the start then a collapse can still happen in a different way but if the owners are trusted then a good security is necessary so that hackers cannot penetrate easily and steal the company's funds. Using the users' funds to improve the company doesn't really sound evil because if it becomes a success, I think the owner will also give a bonus as a way of saying thanks.
What is only not right is if they use the money without the permission of their costumers. It's important to talk about this matter to their costumer first if they have a plan like this and for those who won't agree are free to pull out their money.