I'm just kidding about the 1 in 1000. I have no idea really. Not meant to be taken serious, but successful poly relationships seem to be as rare as pink unicorns.
If you are only browsing in this forum, you are seeing people coming here asking for help with problems. Mostly people new to poly who are just struggling with the basic concepts, as you are.
There are quite a few blogs in the Blogging forum where people are doing OK with poly as a concept. Every relationship has its ups and downs, of course.
As NYCindie said, there are many polyamorous people who are doing fine, but they don't tend to post much, or even be on a forum such as this, which is geared towards working on problems. Personally, at present, I am not having any big problems with being a hinge in a V. I try to post on my blog just to show that. Just a regular life, having dates, hanging out, having fun, being supportive of my 2 partners and receiving support and pleasure in return.
My life isn't consumed with the bare basics of how to handle jealousy, fear of loss, time management and so on. I live with my poly gf of 7 years, she has a bf she sees 1-4 times a month, and I have a bf who I see twice a week. Since my gf travels 20 miles to visit her bf, and he is introverted, I haven't met him. They have been seeing each other close to 2 years. My bf of 5 months visits me at home, so he sees my gf almost every time he visits, they are friends, it's all good.
Poly isn't new though.. is it? It's been written about for 1000's of years I think...
Modern polyamory is actually quite new. When I started it in 1999, there was only one book on the subject, and no websites. Now there are probably a dozen books on the subject, and several websites.
Polygyny is of course, ancient, and has been practiced for thousands of years... but only in a patriarchal mindset where the women are owned by their husbands. A woman having another male lover was strictly taboo, since the patriarch didn't want to raise a child conceived from another man. A woman usually didn't have a choice in husbands, who was instead chosen for her by her own father and tribe, for political ties and economic exchange. Or just as breeders to give the man lots of sons to help with his work, or to go into battle to gain territory.
There is evidence a type of sexual behavior that was more fluid existed pre-patriarchy, where women had choice in partners and children were considered offspring of the tribe, not as being owned by their biological fathers. The book Sex Before Dawn goes into detail about that.
So, poly as presented here on this forum, and in the new books on the subject, began only recently as an outgrowth of feminism, where no one owns women and they are free to make their own choices.
17 years or so since this movement began. And approximately 3500 years since the patriarchy was firmly in place. No wonder there are kinks to be worked out!