Back in 2015, the LA Times reported Musk's companies had received nearly $5 billion in grants. That's taxpayer money. Plus there's the SpaceX contracts--not saying those are unwarranted, certainly SpaceX deserves the contracts more than Boeing--but my point is that it's a huge conflict of interest.
A person receiving very large amounts of money from the government is now deciding which parts of the government should be cut in order to "save taxpayers money".
If this sounds like something that would only happen in a place like Russia, or the DRC, it's because it's something that would only happen in those places.
In other democratic countries you go to jail for this sort of thing (i.e., Nicholas Sarkozy in France--not saying the situation is exactly the same, but there's an actual judicial system in place that doesn't exonerate someone just because they're president, like our SCOTUS did).