Is he really worth that, or is it just stock options he owns? Those can very quickly be reduced to near zero, as Elizabeth Holmes infamously demonstrated.
It’s a tad extreme to compare Theranos and Holmes with Musk and either company. SpaceX is possibly profitable with clear delivering results. There’s no comparison there. Even if one of his companies goes belly up, it won’t be a Theranos and Holmes like situation.
I'm by no means saying Elon is untouchable, but theres a slight different between the useful technology that SpaceX and Tesla produce, and the not-so-useful technology that Theranos had.