I'm not sure why you would take that attitude towards pro playing/sportsmen/whatever - if you accept that entertainment is good (in moderation), surely you accept that providing that entertainment is a worthwhile activity too?

I have a stereotypically productive job, and I'm good at it (and enjoy it). Nothing spectacular, but you probably wouldn't sneer at it either. The reality is that I almost certainly bring less useful value to people's lives than a really good quality entertainer.