I think you'll find that the guys who got gyno are a rather small minority on this forum. It's just that many of them naturally make more "noise" about the gyno than all the other guys make about not getting it.
As for it being impossible according to stats, gyno is listed as one of the possible side effects. I personally don't trust Merck when it comes to the probabilities. Sexual side effects also seem much more common than 2%.
As for my own case of gyno, I do admit it might be paranoia. But since I felt my nipples looked suspicious AND I had some of the typical gyno sensations, I didn't dare to continue on finasteride. It was high time to quit anyway, since I had suffered sexual side effects for 6 months (since day 2), and they were definitely not only in my head. Now been completely off proscar for 52 days and I still suffer the sexual side effects but notice no signs of gyno.
I'm not sure exactly what you mean by "hairless men". If you mean guys with little body hair, but full head of hair, they aren't "hairless" because they have low levels of male hormones, but because their hair is less sensitive to male hormones than us male pattern baldness guys. Propecia doesn't knock our DHT from a high level down to normal. It typically lowers the DHT level from normal to very low, which for some people leads to gyno, possibly because estrogen levels rise in some of us?
I wouldnt avoid trying propecia because of the possibility of gyno alone. You won't get huge b**ch tits overnight. It seems to me that most who get gyno have sexual side effects first.So I think you'd be safe from gyno if you have no sexual side effects. I might be wrong here, though, so you may want to do some research on your own.
Some guys get their various hormone levels checked before starting on proscar/propecia, so they can check whether something is wrong if they get worried after being on the treatment for a while. Also I wish I had taken some baseline pics of my chest when I started, not only on my hair. Because when I started worrying about my nipples I had nothing to compare with. So that's another possible safeguard.
EDIT: BTW, I took a look at the thread where you asked about your hairline. I believe it is only a maturing hairline, doesn't look like you're going bald.