This is very true but not well known. People think that when they deposit money in the bank, the money is still theirs. They are wrong. When the money is deposited in the bank, the money then belongs to the bank. The depositor is an unsecured lender to the bank. If the bank runs into financial trouble, the depositor can be left holding the bag. We saw this in Cyprus a few years ago, after which the laws were changed in the EU and US to make it easier for bail-ins to occur to rescue banks. In the US, there is FDIC insurance of up to $250,000, but even if a depositor has coverage, recovering on an insurance claim is time-consuming.
Crypto assets remain in the owner's hands at all times, as long as the owner holds his private keys. When more people truly understand the advantages of bitcoin and other cryptocurrencies, there will be a tidal wave of new investors. Sadly, some people may need to learn a hard lesson before this knowledge becomes widely known.