Exactly, because most newbies only buy their bitcoin and leave it in an exchange without knowing the risk involved. If you leave your bitcoin in an exchange, there's a 50-50 chance of you losing your bitcoin especially, when the exchange get hacked or pulls an exit scam.
It is not recommended to store Bitcoin on an exchange, and it is very risky in the event of a hack.
But now some of the top exchanges have put collateral on their coins in case of a hack,
so holders in CEXs don't have to worry about their money, it will still be in your wallet.
Exchange security in the past was very bad with hacks that occurred and even stopped operating after being hacked because it was bankrupt