I have worked for and/or audited the majority of exchanges, that mostly white-label a much smaller number of players.

I have yet to see a single one, not one, that had a system of custody that did not allow any one of hundreds of people, most not even employees, to walk away with all of the funds.

There are no standards for security that apply to crypto custodians and the mostly fail to do the bare minimums.

If you use even a top ten custodian, operate under the assumption that the funds are in multi billion dollar plaintext wallets sitting on AWS servers the whole team has ssh access to from the same laptops they "npm install" random shit to all day.

Honestly if you do not feel confident custodying crypto yourself, you should probably not own any.

And if you do feel confident, you probably shouldn't own crypto either.

Even if you are not hacked, or otherwise lose access to the funds, they are not unlikely to become worthless simply due to the system with the stable coins collapsing.

The liquidity can easily disappear, much more so than with Fiat currency or other assets linked to real economies.

You cannot protect yourself from being scammed in that way, even if you do hold on to your keys.