Well from my limited understanding it seems he just had a way of investing in the right companies at first. Like his fortune is basically made from PayPal and after that he invested in Tesla and SpaceX which also became a success (at least in terms of market evaluation). And of course all the (alleged) stock market manipulation and crypto pump&dump he did weren’t bad for his net worth either…

But yeah essentially he got lucky with betting on PayPal and kept his portfolio snowballing from there. At least that is how it looks to me.