Actors have a stereotype of being snobby and sometimes even belittling. There's a preconceived notion that we just walk around like we're all that matters in the world and of course that's far from true. At least for those actors who have a good head on their shoulders....
Yes there are people, just like in any profession, who think a little bit too highly of themselves- and a direct result of this is mistreating their crew. A.K.A. the very people whom without a show could not happen. All performers need to realize that. I think it is so important. Your Stage Managers, tech crew, costume crew, run crew, etc. are your backbone. Just realize this:
WITHOUT THEM YOU DON'T HAVE A SHOW
They are side-by-side with the director throughout the whole process of the show and I would highly doubt you'd want word to get back to the director that you're a disrespectful diva. Am I right?
Directors and all theater staff of course want talented actors- but they also want respectful actors that they can work with.
Also something to keep in mind is:
Who knows where that stage manager that you were rude to will be in 10 years? Who knows when you'll go to an audition and- whoa!- there they are behind the table. And when it comes down to you and one other person for the role, guess who'd get it?
Just be proactive by thinking about such future circumstances and being a respectful person to everyone you interact with. Please and thank you's go a long way and it's something to remember no matter how successful you become.