By my memory of the news at the time he had to take out a significant amount of debt to complete the purchase of Twitter, meaning that failing to make those mind boggling number of millions of dollars per month in debt payments would put him at risk of his assets being seized, such as his significant stake in Tesla.

The overwhelming majority of his wealth is tied up in Tesla stocks, so Tesla doing well while the vanity project he over-borrowed to complete crashes and burns just means either a painfully slow bleeding dry of Elon, or best case for Elon, Tesla manages to increase in value so much that it completely eclipses the loans for Twitter and he can cut his losses. I suppose there's also the possibility that some insane windfall comes to Twitter and it can gain enough value to not be entirely overburdened by Elon's debt