With $1B NW, the government will pay you $150k per day in interest. In stocks you are looking at ~$500k per day (with more risk).
Why you would ever waste your time running a supplement scam, when you passively earn $150k-$500k per day doing nothing, is probably the most perplexing proposition people are making here (which frankly I don't even think they are aware that they are making it).
He could just make an AI startup if he was really interested in doubling his NW.