Malaria is the biggest killer in the world. So, if USA stockpile anti malaria drugs, create a worldwide shortage/demand and sell at a hefty profit. Sounds like an 007 plotline, but wouldn't put it passed Trump. As you say, help his mates out who will then finance his re-election campaign. I do wonder if he is actually taking the drug, or just saying he is. Also, I recall an article stating that Trump has shares in a French pharmaceutical company that produces the drug.
Not the sort of person you want in the spotlight.