By borrowing against their holdings. The framing is deceptive. You can do this too: there is no requirement to have billions in collateral. If you own stocks, your brokerage will lend you money at a very low rate, secured by the equity - typically up to about half of your stocks' worth.
The gotcha is market risk. If there's another crash akin to the housing crisis - and there will be - the bank will liquidate your holdings and possibly leave you on the hook for more. The difference is that Elon may be diversified enough to survive, while less savvy margin-surfers might not.
The gotcha is market risk. If there's another crash akin to the housing crisis - and there will be - the bank will liquidate your holdings and possibly leave you on the hook for more. The difference is that Elon may be diversified enough to survive, while less savvy margin-surfers might not.