Unfortunately because of the TM issues, this domain name doesn't hold any resale value. The other extension that you mention, are actually taken by Ralph Lauren... I would yield with caution on this one.
I know polo is a sport... but the context in which it is being used is, in fact, a TM. You wouldn't say "football sport" or "baseball sport" or "tennis sport" nor would you say "polo sport" if and when referring to it as such. Understand?