Comments like this one aren't fully thought through.

When you give your money a bank they combine it with all other deposits and then loan most of it out. If those loans aren't repaid your bank doesn't have the money to pay back the deposits.

If you don't have your fiat money in your physical possession. Or if you don't have the keys to the safe within which your money is sitting. You don't own fiat money.

Anyone who says "if you don't have the private keys you don't own bitcoin" AND doesn't see the same reality in the fiat banking system is either naive or intentionally ignoring reality.

When your money to your bank it is no longer your money. It becomes numbers on an account record as an amount owed to you by the bank. Same applies to all online bitcoin wallets.