Intelligence and outperforming in stock trading is positively correlated.
I've never seen single person in my life making big money in the stock market but showing lack of intelligence.
Meanwhile, poor people never made money in the stock market. If you ever have seen that then only two cases (short term and small gain) or (you remember it because it's special).
Check the background of every people posting gains (500k<), most of them are actually smart enough to make 6 digits salary regularly, working in financial industry or software engineer for big tech and few million is not a big deal for them.
TL;DR Prerequisite for success in stock market is success.