As I see it, the simple answer is just social status and, by proxy, social opportunity. People who are into cycling often place a ton of importance on how good of an athlete someone is. When I worked in the industry, I routinely saw people get hired or promoted simply because of how fast they were. We called the effect "speed goggles" meaning that you viewed the world through speed-colored glasses. So doping could mean the difference between getting hired or not or gaining stature among a group of peers. Of course no one I met in industry ever openly condoned the practice of doping -- quite the opposite. But their admonitions often seemed to ring hollow. You knew that everyone wanted to be faster. And you knew how much importance people tacitly placed on it.