To me, I think Centralized exchanges are more user-friendly than DEXes due to which people don't like to visit their websites while they can do all the trading on a CEX app like Binance, Kucoin, Hotbit, etc. and that's the only reason why DEXes don't have much volume. Most of the DEXes I've seen are mostly based on Eth smart contracts, but I believe that Eth itself is Centralized so how can those DEXes be called as decentralized ones?