That's because the Hedge Funds are keeping 80-90% of the profit xD Why do you think they are so big..
40% over 15 years is definitely doable LOL. I'm not going to spill the beans, but one of the methods is in your very name! Forex traders make MUCH HIGHER returns than 40%. If a trader is making less than 40% in a year, they don't know how trade. Just being real. I have achieved far better results than 40% over the past few years.
People need to accept the fact that the world is changing, and these things are doable nowadays. If it was 50 years ago, then sure, I would agree that 40% would've been tough to achieve.. But not now.
Just look at Bitcoin lol.