So I want to ask another question. If there is a decentralized exchange: user friendly and easy to use. How can it prove that is it really decentralized? How can you say that 'okay this is really decentralized and I am secure here.'?
Are you blockchain developer? If not, how can believe a person to this?
If you're trading through a website then it has already proved itself not to be decentralised. It may not be custodial but the potential is there for the site to be spoofed or hijacked and off your money goes into the ether.
As for exchanges themselves I'd never use one for significant amounts. I would seek out OTC options where you get a live person assigned to you rather than winding up as a ticket number.