Just asking you a simple question;
What do Prime trust do that you can't do as an individual?
You chose crypto because there is an option to have full control of your funds, why then would you then go ahead and put trust in a custodial service with your crypto?
Because many many users dont want custody - they dont trust themselves. Prime Trust seem to be highly trust-worthy. And post after post here warn about building exchanges and how difficult it is to keep private keys safe (though I would like to know why this is the case).