I've actually found that while most roadies are fairly cool there is a bit more pretentiousness among them then other aspects of the sport. Actually had a conversation with a guy (spouse of a friend) who asked if I like to ride bikes, told him sure, he response was "but do you really ride a bike" not certain what he meant I told him yeah, whatever kind of riding I'm in. "yeah but can you ride a road bike?" My only mental thought was that I only have 2 of those in my dozen+ collection before answering yes. Honestly a cool guy but road is everything. Working in shops roadies could often be the biggest hassle; those who saw me at the group rides on a regular basis were typically chill and easy to help but a good number who didn't know I rode road often seemed like they needed to be judgemental over if a repair would be good enough or if I knew what I was doing. Only other group that seemed to be as freaky over the quality of their repairs were the DHers though they're the group that probably should be and from them I get it. There's also the MUP roadies who really have a complete attitude over anyone who might be in the way or that they have to slow down for or who aren't perfectly on their side; I know there's proper etiquette but don't expect it from a 7yo who's parent is trying to deal with a 5yo with training wheels, it's multi-use for a reason, slow down and go around and move on without a nasty comment.
Road is my favorite aspect of the sport but I think the reputation for snobbery or arrogance isn't completely unearned; though as others have mentioned others can also be over sensative when a wave or a nod isn't returned because you're too busy trying to set a personal best or up your speed to notice and that's a part of what makes cycling fun.

Agreed