
Some people take steroids because they are extremely competitive and want to win, like athletes such as bodybuilders, baseball players, football players and others. The think it is the only way to get stronger and they want to obtain as much strength as they can. Some athletes are so eager to win they'll do whatever they need to do and that includes performance enhancements.
Another reason why some people take steroids is because in the past they have expierenced sexual or physical abuse. They feel they need to be musculare for safety reasons, they feel they can actually protect themself. They wont be attacked or abused as much if they have strength, they feel, so that's why they take steorids.
Another reason is because "some adolescents abuse steroids as part of a pattern of high-risk behaviors. These adolescents also take risks such as drinking and driving, carrying a gun, not wearing a helmet on a motorcycle, and abusing other illicit drugs."
http://www.pwc.k12.nf.ca/PROJECTS/b2201/moore/steroids/page2.htm
http://alcoholism.about.com/cs/steroids/f/steroids_faq04.htm