Is Hackey Sack-ing a sport, really?

My roommate is seriously obsessed with the hackey sack. He is a videographer, and while he waits for things to load on his computer, he stops and hacks for a while. He plans nightly outings with Mike and their friends to go play hackey sack. They invited me to go tonight, but seriously, it is freaking cold outside! Why can't they just hackey in the house? Why do they feel the need to invite people from 20 miles away to drive up here and hackey with them? Why is he so determined to walk all over Del Mar to find the perfect lighted area to play hackey sack at night? I really just don't get it. I mean, if it was a sport, I guess I could understand wanting to better yourself. But hackey sack seems to me like a silly hobby, like yo-yo or juggling. Would you really devote hours and hours per day to it? It's so beyond me...