Traditional centralized exchanges have downfalls as they hold single central server control. It has many loopholes for security and privacy risks.
IMO, not only CEX, DEX also has its risks and loopholes for security. You don't carelessly connect your private wallets to unknown DEX, it's possible to hack. Hackers always have their own ways to steal people's money both in CEX or DEX. So, actually, both DEX and CEX have the same issues related to security problems.
Anyway, how do you know CEX downfalls? Do you have read the information from a certain source? Or do you do your own research? Please don't speculate carelessly, show the evidence.