These days I'm suspicious of anyone who makes a living off their body. In that regard, Tom Cruise and Barry Bonds are under the same pressure to obtain a body that can make the difference between earning 3 million in one year and 30 million in one year. In fact, the pressures on movie stars are greater. An athlete's professional concerns are focused solely on what's under the skin, whereas someone in TV/Movies is judged not only on shape/weight/musculature but also on skin/hair/eyes/teeth/proportions on the surface.
Since actors and actresses are already undergoing a battery of other cosmetic enhancements for the superficial characteristics, it's trivial to apply the same approach to body chemistry. Why would someone willing to let a guy with a knife cut and re-shape their facial features balk at ingesting/injecting a few substances on a predictable cycle to safeguard their multimillion-dollar earning potential?
And we all know when you get up to a certain amount of wealth and public influence, there is a different set of laws than there would be for some guy distributing governmentally-disapproved substances in an urban environment.