These people say, "Well, it's not that much money, and I can afford to lose it!" which really isn't true. Hundreds or thousands of dollars is a lot of money, and while I can afford to lose it (and indeed, at this point in my life, my portfolio can gain or lose the cost of a new car, on a daily basis) someone in their 20's really can't, unless they are a Billionaire wunderkind.
I finally grew up and realized that I wasn't going to beat the market, that I wasn't some financial boy-genius who was going to stock-pick his way to the top. I realized that a better alternative for the amateur investor was to diversify my portfolio among a plethora of things - stocks, bonds, government bonds, mutual funds, insurance, and real estate.