There is nothing about banks that "suck". A bank is a business. If you want to buy a bank yourself, go ahead. You can search "banks for sale" on any search engine and will be able to find a large number for sale.
You will need to take deposits and make loans. To get deposits, you will need to get people to trust you to take their money for safe keeping. Once you get enough deposits, you can loan those deposits out to other people. You pay the people who give you money for safe keeping an interest rate (could be 0.01%) and loan the money out at an interest rate (3%+) and then take the spread.
You will do well if everyone pays you back and people keep their trust in you. If you make stupid loans, as many banks did leading up to 2008, you may lose so much money that you can't cover the deposits.
If you don't have the Federal Reserve/government to back you up in that situation, then you will lose people's deposits.
If you loan money out long term and take in money short term (via deposit) and people lose faith in you and everyone comes in to take their money out, you will experience a "run on the bank" and could end up having to tell people that you don't have the money to give them as shown nicely in "It's a Wonderful Life"
https://www.youtube.com/watch?v=iPkJH6BT7dMNow, as a depositor, would you put your money in a bank that had no Fed backing or one that did? In the US, we have FDIC insurance so if a bank royally screws up and lends money to people who don't pay it back, the depositors can still get their money out.
As part of that, when you own a US bank, you can't make stupid loans. You can't go loaning money out to your friends who aren't going to pay you back. You get regulated. The government comes in an audits you every few months. They go through all your loans and balances and make sure you aren't screwing everything up. And if you are screwing up, they will shut you down before they think you will lose all the money and they will usually sell or merge your bank with a decent one to clean up the mess.
You agree to submit to all that if you own a bank that takes FDIC insurance and government loans.
You don't need to do any of that, of course. If you want to start your own bank without any of that regulation, just convince a bunch of friends to deposit money with you. You can loan it out to other friends. If those friends use that loaned money to buy things from other people you know and you can convince those people to give they money to you on deposit, you can reloan the same money out again.
And there you go, you are a bank without regulation and without any reserve ratio. You can loan out money at an interest rate, get it back with deposits, loan the same money out again, get it back, loan it out again, etc. You are creating money "out of thin air" with no reserve ratio.
You will need to convince people to deposit their money with you, of course, and you better not make many bad loans.
You could do it with bitcoin if you wanted. Take 100 bitcoins on deposit from Person #1. Give him 1% a year in interest for it. Loan out the 100 bitcoins to person #2 at 3% interest. Person #2 buys something from Person #3. Get Person #3 to deposit the 100 bitcoins with you. Loan out the 100 bitcoins to Person #4. Person #4 buys something from Person #5. Get Person #5 to deposit their bitcoins with you.
At the end, you have 200 bitcoins loaned out (to #2, #4) and people have 300 bitcoins deposited with you (#1, #3, #5). And you actually have 100 bitcoins on deposit. There are only 100 bitcoins required for this example.
You can do that forever. And it can work if everyone pays you back and people don't withdraw too much. For example, imagine you did it until there were 100,000 bitcoins loaned out and people had 100,100 bitcoins deposited with you. You would still only have 100 bitcoins on deposit and only 100 bitcoins are needed to do all that lending and depositing.
Ta da, you have a bitcoin bank with a fraction reserve lending system, a money multiplier and everything else.
Now, the questions to you are...
what is the value of bitcoin if anyone can borrow as much as they want at a low interest rate?
does it matter how many bitcoins there actually are when this is going on?
Everything is fine as long as people don't ask to withdraw more than 100 bitcoins at a time and all loans are paid back.
This is how banking systems work at their core.
Now, this is different from central banks. You don't deposit your money with central banks. Central banks exist to keep the banking system from falling apart. Rules are set to determine all sorts of things that relate to banks to keep the system from blowing up. You don't need a central bank but without something like it, you end up with a system where people create banks, make stupid loans and lose everyone's money.
Many countries have a completely government controlled banking system. In the US, it is a mix of public/private institutions and you can start your own bank (or credit union or whatnot).