I’m not defending Musk but I think your figures might be wrong. Are you citing revenue or profit? Revenue last year was way more than 15 billion and profit was way less
Edit: actually, GAAP income was 15 billion but that just open up a whole nerdy accounting argument about GAAP principles and how the US does things differently from others.
Also, he would make the 50 billion over a decade or so, meaning it’s about 1/3rd of profits annually, assuming they maintain profitability close to what they had last year.