Because banks are guaranteed by the FDIC.

Because banks pay for this insurance, and as a result, have to have a huge amount of transparency.

Because most of the liabilities that banks make are backed up by actual concrete assets. There's absolutely no reason that BTC couldn't drop by 99% (and still even leave cryptocurrencies as perfectly valid payment systems), but an apartment in Manhattan will always have value. More, banks write mortgages on significantly less than the value of the properties they are financing.

The concept of fractional reserve banking has been around for over 300 years. All your questions are well-known and were answered definitively generations ago.

My theory is that you have never taken a course in economics, or studied it, and made no attempt to answer your own question before you asked it. Am I right?