That's why people with significant amount of real money usually store it in properly secured and insured banks and similar institutions, not in a locker rented from some guy they never met. Unless, of course, they can't go into a bank for some reason - like having problems with The Law.
I can only presume that Bitcoin, to what extent it's spent on real transactions, is disproportionately favored by the type of person who would not put their money in a bank account.
