All these stock trading books yet people still fail horribly

Is it because the books are frauds and don't teach you anything? Or because people are either stupid, lack self-discipline or both? My dad's doing stocks, he's a "day trader" and he's failing miserably. He's been slowly losing his big sum of money since he quit his job a year ago. Despite having a pile of books on stock trading. He's also terrible at math. I guess he's not "with the times", I can imagine any idiot could've selected a random tech stock and made money during the dotcom times, but now it's probably not something you can do casually. Good thing I can stop worrying about that in 2 years.