Bitcoin was designed to allow people do whatever they want with their money, so if some people want to start a bank, that's okay, it's their right. Bitcoin banks have already been here for a while in a form of online wallets and custodial services.
People are using them because they are too scared to handle their coins by themselves, but it's a lose-lose situation - they risk by entrusting their coins with third parties, but they would also risk if they hold their own coins, because they are noobs. IMO this is one of the biggest problems with Bitcoin - user experience can be very harsh as some mistakes will lead to permanent loss of funds.