They can, but to reach the highest level in this game, you absolutely must have a gambler mindset, who is willing to lose his shirt, pants and possibly wife and kids. If you don't like that idea, don't even initiate the learning process. Just invest long-term and enjoy a normal life.
Stupidest advice I have ever heard. To succeed consistently in trading, not investing, you need to have mind set of people like RenTech crew.
Gamblers eventually blow up.
