Why do sprinters take drugs?

Because certain anabolic steroids can allow someone to effectively exceed their genetic potential. In fact it is possible on a 10 week cycle of steroids to gain as much muscle mass as they would gain in 2 years. Because it has become so popular, most sports people have to use it to catch up with the field. Not to mention when followed correctly steroids often have little long term side effects while it may be the difference between earning $50,000 a year and earning 50,000,000 a year.