Even though this is a common sentiment among crypto enthusiasts, these very same users are actually using centralized exchange platforms to keep their money. It may not be the bank holding their funds, but those funds are still being held, only now by the operators of the exchange.
An additional threat to these centralized exchanges are hackers. Security breaches have been reported by many well-known exchanges, including Bitfinex, and more recently, NiceHash.
As crypto’s popularity and adoption grows, so too does the need to have a safe and secure decentralized method to convert your fiat to crypto and vice versa. Blockchain seems to be the answer as its completely decentralized, which is one of its selling points, which will allow users complete control over what happens to the funds.
Yes, I always recommended to use decentralized exchanges if you need to trade. Good choices include Waves and Etherdelta. P2P exchange on this forum can also be beneficial for small purchases.