Remember, all this happened because he joked on Twitter about buying Twitter to temporarily spike his Twitter stock. This is blatantly insider trading, and the sort of thing the SEC loves punishing people for.

This put Elon in a tricky place. He could say he was joking, and risk getting investigated by the SEC. Or he could double down, and actually buy Twitter to prove he wasn't lying to boost his stock price. These were both horrible options for Elon. But being investigated by the SEC is the type of thing that rich people have nightmares about.

So he was forced to buy Twitter. He could not afford Twitter. So he was forced to engage in a leveraged buyout, meaning he had to pay a big chunk of the check in Tesla stock. This was a shit deal for Elon. Twitter was well known for essentially being at the peak of it's profitability, and the previous owners were looking for a nice exit. They were happy to sell the company to Elon for what was probably the highest price tag Twitter would ever have.

What this meant for Elon, was he had just used several billion dollars of his actually profitable company, and had to tie it's ankles to a company that would only drop in value. (and a company he had no idea how to run.) If Twitter drowns, Tesla does too.