is Ballroom Dancing a sport

Don't know, but trolling obviously is!

Well actually, there are champion sumo wrestlers that hail from the asian countries, and I suppose you could call some of them overweight. If you do, just don't stick around for long, or you may not be dancing for a few weeks

But otherwise I agree that dancing is a sport when taken to the competitive level. About any sport I can think of has a set of rules and guidlines to 'play'. At the competitive level the rules are subjective baised on the patterns and judges.

Social dancing could be compared to a pickup game of any sport, people are more interested in enjoying themselves on the floor than concerned with how they look and the technicallity of the performance.

The problem with this question is that you have to define the word 'sport'.
We accept ballet is an art form, not a sport, and competitve ballroom dancing is a very close cousin.
Of course, there are elements common with sport - the mental and physical challenge and all that goes with those things, but the over-riding criterion for success in dancing is that you LOOK good. There are no objective criteria.
Some other sports are the same - diving, gymnastics and ice dancing come to mind.
But for me (and i accept that this is purely a personal position) real sports involve fastest, longest, highest.
Michael Johnson would be eliminated in the 1st round of the 400 metres if the criteria used for dancing were applied as he has the 'wrong' style of running. And who cares if the javeline gold medallist isn't smiling?
Dancing is primarily an art form performed for the pleasure of the competitors and spectators