Buying stock is an investment, so they still have risk
if someone makes 3mil a week then they are making 428,571 a day
which means that for each stock you get paid 4,285 a week and the stock buy price is just over 100k
if they take a hit you will probably be paid less then that, but if they invest that 100k and dont get hit you could end up making a fair bit of profit over time.