Good to know. Is the I in INTP what gives us so much trouble, or do some of the other letters contribute as well? I feel like the T part is my biggest barrier, honestly. The I just makes the T so much worse.
It's probably not the 'I' unless you are extreme in that regard. I have often tested on the cusp of E and I, although I'm definitely I, by such indicators as "people / parties usually wear me out, they do not energize me." "I need my alone time, a lot." There have been a number of times in my life where I've exerted enormous amounts of effort to overcome 'I' issues, just going and attempting to socialize with people by sheer force of discipline. Because I perceived myself as an anti-social nerd, I knew it made me unhappy, and I was damned if I was just going to leave things that way. I was ruthless about eliminating imperfections in my character; that's how I saw it, at any rate.
It's the NT, I think. I think tons more than most people do. Even if I try to restrict my mouth to the usual social graces, I'm simply interested in a lot of things that "normal people" are not, and vice versa. Most random people in the real world bore me. I'm not 'E' enough to be inherently interested in people for their own sake, for their own varieties, not at all. They are a strain. Dealing with people who don't understand or get what I'm talking about, are a strain. I can do it, I've amassed plenty of insights and survival skills over the years, but I'm going to be happy when I'm not having to bother with some tedious interaction anymore.
I don't think common interests and hobbies are enough. That's merely a starting point. I think shared values are more important. For instance, I got kicked out of a board gaming group a few years ago. My NT sort of "hardcore" way of utilizing board games as intellectual exercises, probably offended some 'F' in the group and then they wanted to get rid of me. They didn't say much about it either, they were pretty two-faced and sprung it on me, fairly suddenly from my perspective. Guess they didn't get any memo about talking to people about problems you're having with them, instead of bottling and resenting. Whatever. I learned the hard way that those people were not actually my friends. They were just people I was playing board games at the same time with them, occupying the same proximate physical space together.
My board game culture is 'old school', back from the time as a kid when I was a real nerd and few people did that sort of thing. So it's my board gaming culture to accept that people might be sorta weird or socially stunted. There's a group I've played with down in Melbourne FL when I visit in the winter, that's more like "nerdy board gaming as I remember it". Someone's seriously autistic, someone else is trying to do all the moves on behalf of a newbie because he can't keep his ego in check, whatever, it's all good. I might say something, in fact I did say something, but it's nothing I'd try to kick someone out for. And it did lead to an interesting battle over attitudes towards rules once.
Anyways... that chapter for me is 'done' and I don't look for board games as a hobby outlet in recent years. I learned some game design things from it and that was fine.
Most of my face-to-face intellectual stimulation has come from the Asheville Skeptics and the Western NC Humanists. People are pretty rational in those venues and that really helps. I don't quite get a complete social life out of that stuff, and for reasons I don't quite understand and somewhat irk me, I never get a date. No eligible women showing up to these groups for some reason. It's been a problem with almost all of my hobbies, actually. Martial arts, breaking necks? Eh, no women. Go figure. I don't know.
Anyways, my intellectual colleagues with shared values keep me sane. We don't end up having a lot of unstructured fun together though. I have my own limitations in that regard, very little money to go out and about to do anything.
I live out of my car with my dog. I have some friends that have lived in similar circumstances to myself. We were all hanging out around Harris Teeter, a grocery store that is permissive about our use of their electricity and wifi. I think of us as the "good ones" who aren't causing any problems, as opposed to the drug-addled "skeezers" who were making an eyesore of the place, or even offering some threat value at times. Store had to get rid of those and I don't blame them. None of my friends are riffraff and I don't want those people around, because they will ruin my good situation down at Harris Teeter. They already took out a picnic table last year, the one that had the best wifi signal, because the skeezers were getting too comfortable over there. They could do things like that again, if they had to. Surveillance on the other half of the store is better though, so I think mostly they're scared off and don't want to hang out. Good!
Anyways that's intended as an example of "similar values" where I've made friends. Yeah, I do have friends. I'm just not having enough fun, and I've never got a date.
I'll be your friend 
No, I'll be your friend 
There are 2 ways to make a friend this way: broadcast those interests and goals to entice them to make the move, or recognize them in others so you can. My interests are ecology, people, music, arguing with random people on the internet to learn and teach them things, non-traditional agriculture, and novelty/new things in general. I'm also a damned good listener. 
