Can he? He definitely has the potential to be massively wealthy. If Tesla/SpaceX/BoringCo/etc exit at some point he'll walk away with '*&^@ you money', but until then he doesn't seem to have that much. According to Bloomberg he's in debt with personal loans to the tune of hundreds of millions of dollars[1].

To be honest though, I don't really understand how normal money-you-buy-stuff-with works for people who are billionaires when most of their wealth is in stock and options.

[1] https://www.bloomberg.com/news/articles/2018-08-16/musk-pick...