Some of the exchanges are actually trustworthy, but the question is what you want to exchange it for.

If you want to flip it for fiat, most exchanges are ruled out because of the missing fiat on-/off-ramp. Also, you'll have to do KYC.

It also depends on which country you're in, but in general I would advise you to exchange such a large sum in batches, and spread it via multiple exchanges to reduce risk.