This is an awfully bad idea. Keeping fiat money at home makes it easy to be stolen by thieves. Keeping fiat money at home means that if the home burns down the money is also gone. Even more, at least in Europe, fiat kept in banks is "insured by the state/government" until a limit of 100k/person/bank.
What I expect bitcoiners do is to keep in bitcoin the money they afford to hold for more than 4 years and maybe keep in fiat the rest. But everybody should make his own decision whether / how much to invest.
The rest, if they have big bucks, they either afford those peanuts the banks are taking, either diversify in gold, art, real estate, stocks, bonds and maybe other things too.