How is dance a sport? opinions?

[Volley Girl #38]

im not trying to be disrespectful but im not gonna lie i dont see dance as a sport. i dont see gymnastics or cheerleading sports either. i see those more as art forms. i have a few friends that are dancers and this always gets brought up on how dance is a sport but i dont think it is. and the main argument my friends give is because dance, cheerleading, and gymnastics and are so much harder than football, soccer etc. but last time i checked a sport wasnt considered a sport by how difficult it is. i play volleyball and a good portion of the population consider that a sport and volleyball is not that hard, in fact its not that hard at all u just have to know control. so i was wondering y do u guys consider dance, cheerleading, gymnastics or others sports or y not. again trying not to affend anyone.
please elaborate on y ur thinking