I've been saying the same thing OP, and just like Phasmal said, confidence is an important factor for both genders. It's even the same when you try to make friends, you're more likely to become a friend with someone if one of you take the first step, and that's where confidence comes in. A person with confidence can show that they like a person a lot more easier than a sheltered person, since the one with confidence ain't afraid to show it, show it.
THEY'RE SEXY AND THEY KNOW IT!
A confident person can also very easily show his brights sides, which is really handy when around people.