Why Steriods?

Why are wrestlers still using steroids? Let me put it another way, why are specific wrestlers still using steroids? I wouldn't be shocked if Ryback had HGH in his bag because he needs something to get noticed. But Borne? He was already an established guy who was (probably) as high (on the card) as he was going to go. Plus, his spot was specific to someone who can do fancy highspots and appeal to the kids. Nothing is about Roid-Monster would've helped him with those Reqts. The same is even more true with Rey.

 

And what does Orton have to worry about in terms of his spot (I know he also got busted on marijuana but that's beside the point)? His competition (if they are in competition) is Punk. Besides which, he's been their main guy for ever. The office seems to always be looking for an excuse to put a rocket up his ass (as opposed to in his checks). Am I missing something? Are these people using steroids for reasons other than physique?
Also, on a related topic, if WWE is so pissed about the above talent why not just push guys who aren't shooting up or whatever either to set a good example or purely out of spite. The obvious  example is Zig but what about Kofi? Between his partners and the office, he's screwed over more than anyone. Plus, they always seem real high on him. What's the problem? (On a side topic, why aren't they pushing more black wrestlers? They fall all over themselves to push latino talent and I bet the black market is much bigger.).
This became kind of a rant. Basically, what is the psychology behind wrestlers taking steroids in this era?
Thanks.

OK, well first, Borne wasn't busted for steroids, he was busted for synthetic pot.  
The Rey thing is definitely troubling, because he's carrying 230 pounds of muscle on a frame that is built for 120.  The last guy who was walking around like that was Eddie Guerrero, and we all know what happened there.  
Orton's been getting noticeably smaller over the years, but steroids aren't always for building muscle mass.  HGH is just as effective for sheer bulk and can't be traced.  Steroids are often used for speeding up healing and giving a more sculpted look to the frame, and it can be really difficult to just look at someone and say "Oh, they're on steroids."  Guys you'd never think of as being roid-freaks were admittedly on them for years.  You wouldn't think Eddie Guerrero was a big user, but he was a big enough user to kill him.  
Kofi's been screwed over by the Orton incident for a while now, and they just don't see him as a main guy, and obviously Kofi is happy doing what he's doing and won't make waves.  They've got a pretty high concentration of black wrestlers right now, though, with the tag champs, the Primetime Playaz, Mark Henry, AW, Big Zeke, and some of the guys in developmental.