Women love confidence. Most overly-confident (cocky) guys come off jerks. Most women hate guys who aren't sure of themselves or who they are, or second guess themselves.
On a whole, these "cocky jerks" know what they want, and aren't shy about it, and hence the conclusion of sex.
For some reason this quote came to mind (but not really relevant to say the least):
See, there's three kinds of people: dicks, pussies, and assholes. Pussies think everyone can get along, and dicks just want to f*ck all the time without thinking it through. But then you got your assholes, Chuck. And all the assholes want us to sh*t all over everything! So, pussies may get mad at dicks once in a while, because pussies get f***ed by dicks. But dicks also f*ck assholes, Chuck. And if they didn't f*ck the assholes, you know what you'd get? You'd get your dick and your pussy all covered in sh*t!