A bodybuilder is considered an athlete because of the physical envolvment with it all. You can't be a BODYbuilder, withouth involving the BODY.
Sports require Skill, such as throwing, catching, handling a hockey stick, kicking...you name it.
But bodybuilders have to master a few skills themselves.
Posing is a skill, hell some lifting techniques require skill as well, otherwise you get injured.(not to mention mental focus for dieting and contest prep)
It's no different from an olympic sport...example: bobsledding, they practice for months and months, only for a few seconds on the track. (and even there they dont do anythign really "athletic" they sit in a freakin sled and lean from one side to another)...Bodybuilders do the same, they train and prepare for only a short time of competition...we could go on and on, but if Bobsledding could be considered a sport...along with Race Car Driving, Ping Pong, hell even poker and curling and darts....then bodybuilding is a definite shoe-in.
You might look at it as a hobby too, many people lift as a pastime activity, but given the fact that the total body is used and worked and strained constantly, you can't ignore that kind of physical involvement.
If bodybuilding (which comes from hours in the gym) is not considrered a sport...
how can boxing, football, powerlifting, etc. be considered sports? when they all require thier athletes to train in gyms just as much? the only difference is, outside the gym the other guys appy their bodies to a skill, such as throwing, running, etc. Bodybuilders use it towards posing etc. one way or another you're benefiting from the gains/results attained in the gym.
So what is so different?