Thinking back to that presentation in the library makes me smile. What started out as three high school boys skipping class turned out to be the most significant event in our lives. If we had made it to the gym that day instead of the library, more than likely the streets would have swallowed us in the next few years. We never would have become doctors. Everything we needed to start on the road to success was included in one forty-five-minute presentation. And we almost missed it. —We Beat the Street,
Sampson Davis et al

Based on the passage, what is the most important cause that led George and his friends to becoming doctors? Explain your answer in one to two sentences.