I trust myself to manage my own keys, but I acknowledge that I am a VERY exceptional case.
Unless the security of desktop operating systems (*cough* windows *cough*) gets a hell of a lot better, I don't think most people can.
I think that's my point. You have 85% of people who are saying that they will never trust a third party for storing their bitcoins. Naturally, 10 years from now, a percentage of these people will have lost some or all of their bitcoin (whether it be losing paper wallets, hacked computers, system failure, house fire, etc, it's inevitable, and undeniable). We've all lost cash in the past couple years, yet I doubt anyone here has lost cash FROM a bank (Of course, there may be some exceptions for our European friends in Iceland, or Cyprus, but I don't think they're present
I understand people don't want to use a third party, trust me, if it was practical to store my fiat cash myself, I would, but I don't believe it is.