I'm late on this thread, but I think it's a bit obtuse to say that actors have a harder life than anyone else. Forget fame and fortune, few actors who set out for that ever actually achieve it.
So what are you left with?
The responsibility for your own happiness.
I could list 10 other careers off the top of my head where people have a harder life. Is that comparison fair? It's only as fair as the actors who choose to compare themselves with their colleagues.
The ultimate fact remains that life has it's ups and downs. It's part of the human condition. We all have the responsibility to act and react in a way that serves us, makes us happy, or at the very least gets you through the day. We all have those moments of wondering "what if". . . .and you can choose to dwell on that thought and let it spiral up or down, or move on to the next thing in front of you. Do the best you can at any given moment in time, recognize that everyone lives in their own reality, and by all means try to live as gently and with the grace you wish to be remembered by.
If you meet a stage manager who calls better than you, has a better organizational skill set, etc, you can choose to feel insecure, you can choose to learn from them, or you can choose to do nothing at all. Is one option better than the other? That's for you to decide.