I could have written this comment above. One of the problems lies in the fact that "smart" means different things to different people. Firstly, it usually seems to take on the meaning of hard-science smart and, with that, one often finds specialists. I live in a city where every other person I meet literaly has a PhD (or two) but what am I going to talk about with them regarding particle physics or string theory?
If I were to call myself smart, I'd say I'm humanities smart, ie a generalist, ie utterly and insatiably curious. How many others in life have I met like me? Maybe one. That's it, and he's a DN so I don't get to see him much.
We also have to factor in lifestyle. I'm a VA and thus I've moved many times in my life so this doesn't help with the situation. For the last decade, I've accepted way less pay and less hours so that I can have the free time necessary to learn all the things I want to learn - long-term goals, if you will. As a trade-off (and I gladly do it), I live abroad because that's when quality of life goes way up and cost of living goes way down (most of the non-native English speaking world already lives this way, IMO).
In the end, I'm curious enough to take up my own free time, but since I'm also not a shut-in, I seek out ways to socialize with interesting people. The kicker is that most of them are travelers/expats, so they move too.
Recently I met a guy who is both nice and available (even though he moved away the other day), so we'd hang out quite a lot. He didn't have to share my interests or be a generalist or anything. He just had to be agreeable and available, and this surprised me a bit, though I'm not sure why. Not be an a-hole and say "I'm free, let's do something" can be a powerful motivator.