STEP 1: Form a bank.
STEP 2: Round up a bunch of unemployed friends to be "bankers."
STEP 3: Raise $1 billion of equity. (This is the only tricky step. And it's not that tricky. See below.*)
STEP 5: Buy $10 billion of 30-year Treasuries paying 4.45%
STEP 6: Sit back and watch the cash flow in.
At this spread, you should be earning at least 4% per year on your $10 billion of capital, or $400 million. Sure, there's some risk that the Fed will grow a backbone and raise short rates, but there's not much risk. (They have an economy to fix and banks to secretly recapitalize). And in any event, if the Fed raises short rates, making your $1 billion will just take a bit longer. (And if they REALLY raise rates, causing you to actually lose money, it will be someone else's problem.)
You'll have made $400 million in a single year! So pay yourself a fat salary for all your hard work. And pay your "bankers" fat salaries for all their hard work (But don't worry--your bankers won't actually have to do anything. You'll just need one of them to borrow the money from the Fed and buy the Treasuries, which he will be able to do part-time.) At the end of the year, celebrate. It's bonus time!
Don't be greedy. Pay yourself and your bankers the industry-standard compensation ratio of 50% of revenue. Your revenue was $400 million, so that creates a $200 million bonus pool. Pay each of your unemployed friends bankers, say, $1 million. And give yourself the rest for being such a smart entrepreneur and creating all the jobs and value.
Now, you've already made at least $150 million, so it doesn't really matter what happens next. But you're in this for the world's easiest $1 billion, right?
So proceed to Step 7.
STEP 7: Go public. After bonuses, your bank will be earning about $200 million a year, your capital ratio will be super-strong (10% equity-to-debt!), and your balance sheet will be clean as a whistle (all risk-free Treasuries!). So you ought to be able to persuade investors to pay you at least 20-times earnings, or a valuation of $4 billion. Sell 25% of the company for $1 billion.
STEP 8: Use your $1 billion of new equity to borrow another $9 billion at 0.25% from the Fed. Buy another $9 billion of Treasuries. Collect another $400 million a year. Pay yourself and your team bonuses that are twice as large as last year's. You deserve it! And you're now about $500 million to the good.
STEP 9: Wait for your stock to double or triple, which won't take long given your amazing growth trajectory and clean balance sheet. When your market cap hits $10 billion, sell another 10% of the company for $1 billion. Now you're really ready to grow.
STEP 10: If you want to get fancy and get nice profiles written about you in business magazines, start buying branch networks from defunct banks (the FDIC will pay you to take them) and start making actual loans. Also, start hiring trading desks to gamble on things more exotic than Treasuries. Yes, all this sounds risky, but just remember--the risk isn't yours, and you're already $500 million to the good.
STEP 11: Sell $500 million of your stock to a "strategic investor" and let the rest ride. Don't worry, if your traders and loan officers turn out to be idiots or the Fed suddenly raises rates, the taxpayers will handle it. And you've already made your $1 billion.
So, congratulations, you're now a billionaire! Now all there is left to do is celebrate!