With specific regard to the crabby online hams that scream "read the manual!" Here's my take on it...
Amateur Radio is a hobby that is at least 70% experimentation. We build things, we test things, we make them work better, and we scratch our heads when they don't do what they should do. I've spend hours staring at a radio or antenna yelling at it "Why don't you work!??" After spending a few hours working through the problem, I learned how to make it work. Much of the younger generation (and I'm 33 years old) are so damn impatient. They spend 5 minutes fiddling with the radio and then cry on an online forum "Why doesn't my radio do X or Y?" Yeah, in that situation you should get the "RTFM!" answer. On the other hand, if you tell me what you've already tried and obviously you've tried everything you can think of (including RTFM) then you should receive all the help you can get. This is the very basis of "Elmering" - try to figure it out on your own, then learn from someone else.
As for crabby hams on the radio... well I think it boils down to human nature. Take 100 random people and stick them in a room together for a few hours. Quickly you'll see small subgroups begin to form. You'll see a few people that just stay in the corner, and there will surely be a few social butterflies that roam around and talk to everyone. Undoubtedly some new friendships will be made, and more than a few people will absolutely hate each other for no reason at all. This is simply the nature of a social species.
Now, take this same example and apply it to ham radio. On 2-Meters, I pretty much stay on one repeater. This is where most of my "radio friends" can be found. I like most of them, there's a few people on the repeater I can't stand for no other reason than because they annoy me. There's one person that's always right and you couldn't convince him he's wrong if he said the sky was blue. Occasionally we get "outsiders" (new people) that join into the conversation. Sometimes I greet them quickly, other times I sit back and listen. This is the same way I act in person in a crowded room. Now, there's other people on the repeater that are the social butterflies that love to talk to everyone that keys up. There's the wallflower that only talks to one person and signs off when more people join the conversation.
Just as in real life, there are jerks on the radio. These are the people you'd meet anywhere in the real world that just no matter how nice you are to them, they are jerks. We all know "that guy" at our job, or at the grocery store, or even a relative that we all just can't stand to see during the holidays. When you run into those people, in real life or on the air, you can either avoid them or provoke them.
In conclusion (the TL/DR summary): There's crabby people everywhere, not just on ham radio. If you don't like them, don't talk to them. As in real life, find the people that share your common interests and someone you can tolerate and talk to those people instead.