It's actually scientifically proven that men generally overestimate their own attractiveness.
When Men Aren't As Good-Looking As They Think
So you might have thought you were better looking than the girl you approached, but chances are.... nope.
That's because it's the man that has to approach the woman : men know that attractive women get approached by lots of other men, so you got to believe in your chances. For some, that means overestimating themselves. Kind of like a baskebtall player will say "Im the best" just to boost himself to step on the court with confidence, even though everyone (including that guy) know that's not the case.
And as men there is no clear "response" to your attractiveness : you could be the most attractive guy but if you don't have game/status, you might not get her. On the other hand an "unattractive" guy might pull all the bad ones because of his game/status.
So for a man imo there's no way or being "right" when "measuring" your own attractiveness. Women on the other hand know where they stand due to the attention they get, and they can "measure" themselves with whatever "standard of beauty" is out there at the moment. So as a man that has to take the lead role (approach the woman, spit game, etc) in a competition (against all the other men approaching an attractive woman) might as well boost your ego. No point on steppipng on the court saying you're not as good as the others
