"Musk is a billionaire only due to the largess of the American Taxpayer. "
Elon is a billionaire on paper, but that paper is tied to his various business ventures. If he started selling a bunch of stock, those stocks would plummet in value. He has also intertwined his business ventures financially so if one fails, it can drag the others down too leaving him having to ask his friends for some cash loans to feed his kids and make his house payment, again.