I know what it's like and how hard my assistants work, and I try to treat them as fair as possible and make the office a fun environment.
I want to keep my clients happy, and the pressure's on me as the boss to manage my three assistants and make sure that everything is getting done. There's less time for tears and more time for bossing people around.
If my assistant goes off and becomes successful, and people want to work with him, I'd take that as a compliment that I'd trained them well.