For Philosophy's Sake

When I was taking my course in leadership and ethics with the Marine Corps, one of the topics that we touched on was the definition of professionalism. According to the guided discussion we had in class, a professional is someone who performs a job necessary for the successful conduct of society: physicians and surgeons, police officers and justice officials, military personnel, educators, et cetera.

So, I was rolling this around in my head a few days ago, and I stumbled across a thought: if professionals are those who carry out the respected functions necessary to the existence of society and civilization, then is there really such a thing as a professional athlete? After all, athletes serve a purely peripheral, expendable function.

Discuss.