It wasn’t just him though, he put up less than half the money. Other investors and lenders backed that price and hoped to profit after the purchase. I think it’s fair to say that the market valued Twitter + Elon at the price he paid, and was initially willing to pay more than what Twitter was trading at because they bought into the idea that he’d do good things with it.

Elon only wanted to back out after tech stocks overall dropped further following an increase in inflation concerns (they were already down, providing an opportunity for the buyout, but continued to fall after the deal). But most tech stocks have since recovered those losses and the nasdaq is up about 10% from where it was at the time of the deal.