Investing in Bitcoin and also saving money in our banks are two important things, you can't invest in Bitcoin and don't still have some save in your bank that's very wrong, remember you are investing with your leftover fund in bitcoin which is your discretionary income money you won't be needing for a very long time while the one in your bank account is the one you will needing anytime to sort out your personal needs by getting it back either going to bank or by going any point of sales POS joint to withdraw your money while you still accumulate Bitcoin and hodl so it is much important to invest into Bitcoin and also have some huge saves in your bank very very necessary.
You have a point, there must always be Money in your bank account for emergency purposes. Things can happen that you probably don't expect having assets in Bitcoin only might not really save you from the trouble at that moment. The only advantage of having your savings in Bitcoin over saving in a bank account is the profits you can make from the market when the price keeps on increasing, your bank account doesn't add any value to your savings.