If storing completely safely was much easier than now many many more people would put wealth into bitcoin, and that demand would lead to many more places to buy and sell bitcoin. So when the security is there, the rest follows.
you can solve this in two way, make it more easy, or teach to those people how to store your bitcoin safely, the latter has proven to be not a good solution, the former is not really a problem, because come on.... putting your wallet.dat in a usb and don't use it in your infected computer isn't something so sophisticated to understand
i think people simply do not trust bitcoin itself, its unstable nature, more than losing their money for thieves