I know what you mean, just because you are famous and charge a lot of money does not give you license to be rude.
I'm going to use the dreaded "it depends" phrase here, because I kind of disagree with the above in certain cases.
But, so much of this idea of trainers being "really nice" or "really rude" probably depends less on the actual trainer and more on the personalities of the people who meet them.
Simply paying someone a lot of money to help you with your horse, or to improve your own riding, does not mean you are entitled
to have sunshine blown up your skirt.
Of course, some trainers (at all levels) make a good living by working with clients who pay them to make them feel like everything they do is just marvelous. If that's what works for them and their clients, fine. Then again, I've known people who are used to being spoon-fed compliments, who are forced to relocate for a job or whatever and end up in another barn with a trainer who isn't quite so "fluffy." And drama ensues.
Those are the trainers who don't like to waste their time (or their clients' time) sugar-coating things no matter how much money they are being paid. It doesn't
mean they are miserable, mean people all
the time. It doesn't mean they are rude or antisocial. But they're not being paid to be your friend, they're being paid to show you how to be a better rider, or how to do a better job of handling your horse.
Just as there is no "one style of training" that is perfect for all horses, there is no "one style of trainer" that will mesh perfectly with all clients. Some students/clients excel under the tough, demanding, no-nonsense trainer because they feel challenged. . .and yet, a different student with that same trainer may find them "rude" and "mean" because the trainer didn't give them a pat on the head and a cookie every time they did something right.
On the subject of those "meet and greet" with the big-name trainers at various expos. . .I never really understood the appeal of waiting in line for over an hour just to get their autograph or ask them a question about a horse "problem."