It's not the power of convenience that'll make those users deposit cryptocurrencies in Coinbase. It's unawareness. Sure, Coinbase may make them feel really convenient with those stylish buttons and cozy layouts, but if they choose that way, then it's a matter of their ignorance. I bet most of the Coinbase users have no idea why Bitcoin was created or they're in the field just for quick profit.

Needless to say, that the majority hasn't read the whitepaper. (Not proved, but definitely obvious)