Who - It depends on what your goal is. Someone doing this 5-10 times a week will make $1000-2000 a week. Not bad if you just want some extra current income (and assuming you don't FUBAR it too many times). Don't get me wrong, I'm not a daytrader, but this works pretty well for the people who are good at it. And ruins those who aren't. And good luck trying to do your taxes at the end of the year...the schedule D for daytraders looks like a bomb went off.
When everyone actually IS out to get you, being paranoid is just smart thinking.
Moe