I was trained as a neurologist, and then I went into the theater, and if you're brought up to think of yourself as a biological scientist of some sort, pretty well everything else seems frivolous by comparison.
You spend ten years of your life being trained to do one thing, and you're being taught to think that it's the most serious thing that anyone could possibly do, and then suddenly you find yourself doing something that in some respects is the epitome of frivolity.