That is true. Probably by pure volume of trades the CEX order books will always be able to facilitate an order of magnitude more than DEX as they can fulfill or

That is true. Probably by pure volume of trades the CEX order books will always be able to facilitate an order of magnitude more than DEX as they can fulfill orders instantly with almost no fees at all, and many beginners and casual traders with crypto will not bother with or even understand what it means to transact on-chain. But there is a very significant amount of crypto trading occurring on-chain, to the tune of multiple billions of dollars per day.