well it's a matter of choice anybody can choose what to trust either to trust bitcoin or to trust their banks, and many too has developed the habit of saving all their money in cryptocurrency, like bitcoin rather than putting some in the bank and putting some in bitcoin as an investment, though it's not a problem,
The fact that something is a choice doesn't make it the right choice. Using the banks is one thing; you can't avoid them, but trusting them is a whole different thing. I don't know how things are in other countries, but in my country, you'll be delusional if you think you can lie without the banks or only on bitcoin.
What you can do is save all your money in bitcoin, in fact, I advise it. My country is stuck with inflation and a very unstable economy, one of the worst things you can do for your money is save it in our local currency for the long term, especially now with the economic and trade unrest stored up by the trade administration.
Bitcoin is easily liquidable, so it won't be a problem to have all your long-term savings in bitcoin.