Why are young people obsessed with muscles now?

it seems like guys in my grade lately are becoming obessesed with going to the gym and having big muscles as well as taking all these supplements, and wearing all these really gay tight shirts now. Whats the deal with this, people like this used to get made fun of and now all of a sudden its cool? I havent been to the gym once in my life yet i work out in my house every day im 17 and ive got good abs, weigh only 145 pounds, eat what i want and put all this supplement garbage in my body and im fine with it. Obviously its good to excercise but who wants to look like arnold shwarzenegger for gods sake or rambo at this age, its goofy. Also whats the deal with calling other gym goers pinners?