It's not really about that alone.

Musk have a case against him by the SEC (tweeting about taking tesla private), it seems like they can win it, and he might be forced to stop using twitter.

Now I can imagine it hard for the SEC to enforce such a role if it's his private company.

So in a sense he's using that money to secure his best tool to marketing / growth which is definitely worth 50Bn$ for tesla alone (then add all his other ventures now and in the future)