I think many of them are happy with the way they are just the way many of us are happy the way we are.
To think that they don't enjoy parties and nightclubs because I don't enjoy those things, is a failure of theory of mind: It is possible for others to enjoy things I don't like, so I can't apply my own preferences to other people without checking to make sure the preferences are the same. If I say, "I can't stand loud parties; the NTs go to them all the time; if I did that I'd be miserable, so they must be miserable too," is a statement that ignores that NTs are different from me, and enjoy different things.
But they do the same thing to us. They think we must be horribly sad because we don't go to parties or nightclubs (well, most of us don't), because they like those things and we don't, so they think, "I love these things, and those poor autistics can't do them; they must be horribly sad about it, like I would be if I couldn't do those things." But they'd be just as wrong.
NTs live their lives with most of the people they meet being very much like themselves, so when they assume that other people are just the same as they are, as a quick-and-dirty estimate, they are often correct. It's when they meet people who are just different enough to throw off their assumptions that they start getting it wrong.
Many NTs are unhappy, just like many autistics are unhappy. I can't really say "pity" because "pity" has kind of a condescending vibe to it, like I think I'm above them, and I don't think that because I've been unhappy a lot myself and I can't look down on other people for being unhappy.
Admittedly there are some pleasant things about the experience of being autistic that NTs can't experience--the calm of rocking or the sensory thrill of the perfect texture or the absorption of a special interest, for example. On the other hand, we don't get to feel the emotional contagion that NTs experience in groups, and probably won't ever experience what they like about loud, large groups of people. And they don't have the benefit of having a disability, namely the experience of being different, not quite fitting in, and seeing society from a different angle; they're missing the unique perspective we get.
On the whole I think it's a trade-off. Both groups get things the other group doesn't get. That's just life; everybody's got an advantage over someone else in one way or another. Born in America? Advantage. Born with athletic talent? Advantage. Born poor, and learned how to survive? That's not a skill everyone learns. Not that poverty's something I'd want to perpetuate, but it does have its perks... I know, I'm poor myself...
At any rate, nah, I don't think I'd pity them. Nor do I think they should pity me. But many of them do, anyway, because they don't seem to understand that there are many ways to live and be happy and have a satisfying life, and the multiplicity of ways that NTs live are not the only ways to live. We have our own ways; they have theirs; there's a lot of overlap because we're all human. Difference isn't bad, it's just different.