Banks do not look reliable because they are controlled by the state. But some part of the assets may be kept in the bank.
Keeping everything in cryptocurrency is quite dangerous. Assets need to be diversified.
Keeping money in banks is safe but there are many people who prefer investing in cryptos rather than banks. Although crypto is dangerous if you understand the correct position of the market and invest in the right currency like bitcoin it is never dangerous. The government has to pay tax to keep money in the bank there is no such hassle for crypto.
I think this is both relative and subjective at the same time, so everyone should do what pleases them. Keeping the money in the bank is not so bad but have you also thought about the inflation that is plaguing almost all the nations of the world? This is the issue with people keeping their money in the bank where the bank will give them a peanut as the interest accrued even as the bank continues to make huge income from the money, which is the most painful part of it all.
At the same time, cryptocurrency is a very good option, but what if the investment plans fail? This is not so impossible if you look at what happened in the last bull run. There are many investors that has not gained back 20% of the money they lose to various altcoins, not to talk of gaining back the whole 100% this year or next. In many cases, this may not be possible anymore since some altcoins may never hit their ATH again. This is a loss!
So it is not so convenient in the cryptocurrency world as well. But what you never added is the fact that there are other investment opportunities. Instead of we keeping our money in bank and investing everything in cryptocurrencies, why not diversify it? If done properly in at least 5-10 differents sectors, I am sure that nothing adverse can take that way from the person. And this will be a smart move to avoid banks issues and still edge against inflation in a way and try to secure one's future better.