Do you have evidence of Coinbase's solvency? Because it seems to me this is all based on blind trust. If there is real evidence, of course that trumps the blind trust issue, but without it, it's generally a good bet that amateurs lack the skills, experience and resources to ensure proper handling of financial transactions.

Real banks are also not trusted blindly; they get audited a lot by central banks and other regulators. And they still mess up and get flamed to hell for it. The chance that amateurs in a completely unregulated field do it better is very unlikely.