To @Curious T, if talking about convenience, it can't be CEX because why will they require KYC and other shits when DEX are straight to the point? The moment you get on the homepage, you can trade right away. Maybe this is the reason on why their UX are simple to, to make things much quicker. With what I said about CEX, and how popular CEX are, it is only a proof that people can also do hard stuff just to experience that thing they can not see on the other.
I guess you don't understand what convenience is. CEX are more convenient than DEX. "Convenience" doesn't mean which is safer, or which is more private, but which is easier to use. Which of them makes things relatively simpler and easier for users? Users don't have to worry about seed phrase protection. They can trade on the same platform with their funds, and if they want fiat, they can easily sell their coins using the exchange's P2P feature. Convenience has nothing to do with whether the exchange asks for KYC or not. Using CEX is convenient. In fact, custodial custody as a whole is more convenient than self custody.