Now, why would this even be true? Why do nerds have more fun when they're older?
Well, when you are younger it's hard to be into something that is misunderstood, but you get a good close group of friends that way. Over time, you get used to having your own fun without having to depend on the mainstream ideas of what's ideal. Do you know what you want? Do you know what you think? Do you care if anyone else validates it? No? Then you're more likely to be happy than the guy who needs to be reaffirmed about his life choices.
Over time, doubts occur in life because the unexpected happens. You can do you best to plan out everything the way you've been taught it's "supposed" to be, but it never really turns out that way. And I think nerds, or people that our more independent of thought in general, know that. Knowing that makes it easier to take the punches and move on.
Also, nerds are better making their own fun. My mother taught me that one and she's right!