I hope this image of the stuck up, nerdy, nuke is a grossly overstated stereotype.
In my engineering department - 40-odd people - and realizing that there's overlap between them, we had...
power lifters/bodybuilders
alcoholics
gun owners
martial artists
alcoholics
motorcyclists
marathoner/biathlon/triathlon competitors
WoW players
alcoholics
photographers
off-roaders
bicyclists
fishermen
alcoholics
boaters
computer nerds
astronomy geeks
aquarium (what the hell is it with submariners and aquariums?) people
hunters
hikers
campers
alcoholics
Dungeons & Dragons players
console gamers
beer brewers
car tinkering people
street racers
alcoholics
...and I'm sure I've forgotten a few. So, really, it's a diverse group of people. As for stuck up, well. Throughout the entire training pipeline, you're told you're the best of the best. The Navy has picked you for its elite few! And you're surrounded by (relatively) smart people while you're in the pipeline. I'll be honest, the pipeline was the first time I felt like I was challenged academically by my peers, as far as keeping ahead of the group went.
Anyway, all of that aside, when you get out to the fleet, you realize (to your growing horror) that the Navy wasn't kidding when it said you - and your buddy that you last saw projectile vomiting from the 2nd floor of his apartment at Prototype following the graduation party - are really the best and the brightest. And that you, with a high school diploma and two years of training, are going to be operating a portable nuclear reactor.
There's really two ways to respond to that. Pants-filling 'OMG TERROR what do I doooooooo?!,' or taking the challenge by the throat, grabbing its testicles firmly in one hand, and twisting until it submits to you and you have, indeed, qualified to operate a plant (and gotten your fish). The first option tends to not be the one chosen by most nukes, although we did have two or three get disqualified and sent to the surface fleet (there's another reason submariners think we're better; the surface navy is where we dump the dumb nukes).
And doing the second, when combined with the rest of the pipeline, tends to produce just a little bit of I-can-do-it self-confidence that verges on excessive ego. Really, looking back on my time in, and comparing it to how I used to think before I joined, is... Very amusing. Give me a reason, give me a couple months, give me the books, and I can be a theoretical subject expert on almost anything these days. Give me a couple more months, and I can probably do the job with something approaching professional competence.
It's not really the "knowledge" that the pipeline and training process gives you that gives you that "stuck up" sensation. It's the fact that you've learned what your limits are, and how to push them. Not everyone does. Hell, not every nuke does. But take a random nuke, drop them into any professional, technical field, and they can probably succeed in it after a bit of training and experience.