America loves a winner but loves it even more when a winner gets caught doing some shit to make him that way. When they get caught, it makes all the "normal" people say they could do what they did if they used the same substances. Why do you think the *lesser* individuals that get caught go through the grinder quick, whereas the top level individuals might as well be chained to a back of a truck and dragged through the parking lot for a few months.
Look at the size and speed of everyone in the NFL and how its changed over the last 30-40 years. Its pretty blatant. Also, I've known some people who I played football with in HS that went on to certain pro teams. Lets just say when they were first going through "training" after being drafted, their strength, speed, and size went up a LOT. I firmly believe use is beyond just "normal" in college ball, but its minor compared to what happens in the NFL... Completely different levels. I actually think there's someone that interacts with certain teams/players that are specialists in that area, whereas the college level is more of a friend using it and everyone wants to be top of their game so they partake (though I wouldn't be surprised if it was more than this). But I think this is true for any and all sports that has 10,000 people wanting your exact spot. Too much competition and money not to do everything to stay on top.
Like Krazi said, everyone's on it, but you only hear about the people that are caught.