Question for online daters: Why look at someone's profile a LOT, but never contact?

Ok guys, I have a question: WHY do you keep looking at someone's profile, but never contact them? I use Yahoo Personals, and I'm finding a lot of the same guys keep looking at my profile, but never contact me. I know you're going to probably say, because they're shy. (These are mid-20, early 30's guys too!!!) Well....if you're REALLY interested in someone, why not take a risk? Not to be lame or cheesy: to quote Kelly Clarkson: "I'm looking for a man by my side, not a boy who runs and hides".