""If more science graduates are desired, the findings suggest the importance of policies at younger ages that lead students to enter college better prepared (PDF) to study science.""
Secondary and college students are subjected to only the most minimal of discouragement compared with what they will experience in the real world of academic and industrial science. Research progress is based on multiple failures, punctuated by brief, intense flashes of insight. There is a lot of chance involved, because there is a great deal of educated guesswork leading to theories and experiments.
High school, and college barely begin to prepare you for grad school and life in the real world.