Quick Google search: "Generally, there are no restrictions on foreign ownership of a company formed in the United States. The procedure for a foreign citizen to form a company in the US is the same as for a US resident."
Broadcast news is one of the exceptions:
Under federal regulations an alien may not own more than 20% of a broadcast license.
https://www.latimes.com/archives/la-xpm-1985-09-04-mn-23112-story.html
The missing link is to recognize that billionaires are citizens only technically. They have no interest in the well-being of their nation (or even their planet), nor are they subject to any of its laws.
