You have found a gap in the market but do you think this gap is creating enough space to enter into this market? I guess no! There are several other factors that are considered by the traders before they jump into an exchange. With the rise of kyc/aml monitoring among the centralized exchanges, defi non custodial exchanges are becoming a predominant player in the crypto market and I foresee this practice will slowly take over the entire crypto market where you do not have send money to exchange accounts before start trading.
No KYC procedure is definitely an advantage for DEXes, but I'm really curious what will happen if tomorrow EU parliament votes yes for the law that will forbid anonymous crypto transactions. Maybe then DEXes will have to enforce KYC rules too. I know that you can trade on a DEX by directly interacting with a smart contract, but how many people know how to do that?
So a solution is already here. But why Coinbase or Binance still managing to churn out volumes? It's called endowment effect. Go ahead and search google for a little business lesson.
As for the original question, I think that high volume traders like security. We all saw what happened when
Binance was hacked and none of their customer lost their money. I like that security and I'm willing to pay a little higher trading fee if I know that my money is safe.