I don’t think there’s any one reason. The reasons you and others have described all come into play at different times.
I grew up during the feminist era, and I understood from an early age that women—at least the women I knew—didn’t like it. They found it annoying at best, threatening and dangerous at worst. There was a fear that the guy would follow up his whistle with more aggressive action if there was no one else around.
When I see a beautiful woman, who is sexually attractive (and that bar isn’t hard to meet), I, well, to make no bones about it… ok, to make bones about it, think something like, ‘I wouldn’t kick her out of bed.’ Usually it’s a bit cruder than that. I fantasize a teeny bit about what that might be like—picking her up and taking her home, caveman style almost. Then I think, ‘that’s never going to happen,’ and I move on. I’ve never whistled or cat-called.
The idea that there are men out there who can approach a stranger on the street and charm her into their bed with mere words used to make me pretty jealous. It seemed like such a powerful and ego-reinforcing thing to be able to do. However, at a fundamental level, it was all just a fantasy and not something I was truly interested in. Kind of like fantasizing about climbing Mt. Everest. Sounds cool. Not gonna happen.
What I was and am really interested in, as unmanly as it may sound, is a relationship. I want to get to know a woman and come to love her by finding out she’s a really cool person. A catcall isn’t going to get me there.
But most men don’t think that way in public. In public, as @marinelife said, they tend to be in groups and that’s always a competition for manliness. Or the appearance of manliness. I think many of these men are very respectful of the women in their lives in private. Not all, of course. There are many who think women are servants.
And it’s funny, because if you whistle or catcall a woman you know; a woman you love; it is often received positively. She glows in your regard. But that’s private where it isn’t embarrassing.
There is also something just the opposite of good that happens with some guys, I believe. I think some guys believe the hype that a woman should just fall into their arms. Every woman should want to fuck them. But the don’t, and that frustrates some men, no end. These men tend to never have had good relationships with women. They were probably abused or abandoned by their mothers. They have no clue how to act around women.
Something in them snaps at some point, and they decide it’s too much. They are tired of not getting what they want, and so they take it. For them, the catcall is malicious. Maybe a test to see how the woman will react. Is she afraid or is she innocent or is she strong? These men might then go after the low-hanging fruit, so-to-speak. Try to capture them and rape them. In some cases—probably very few—a catcall can be quite malicious, and a prelude to worse.
I think a lot of things are going on when a man catcalls. I think underneath it is the same fantasy I have. On top of that is the jealousy of men who have the skills to pick up women. Mixed in is the idea of showing other guys how bold you are when you see a hot woman. And, unfortunately, I think for some men, there’s something more sinister going on.
GQ, by the way—one of the very very few I have ever given out.