the great thing is that Bitcoin lets you be your own bank.. but you don't have to be! You just need to do your due diligence if you're going to trust a "bitcoin bank," much like how back before the FDIC, people needed to know how a bank was doing financially before deciding to open an account.
at the moment, we're not at the point where we can fully rely on any custody services. we're still in the "enthusiast phase".
once things become a bit more mainstream, I would think the vast majority of people will want to outsource security of funds to professionals.. division of labor and all