I think your experience is highly admirable. But I think even you have to admit that most people, regardless of background, do not have the sort of will power

I think your experience is highly admirable. But I think even you have to admit that most people, regardless of background, do not have the sort of will power and drive you exhibited. So yes, any particular person could overcome the obstacles in their path. But most will not. And it's the "most" that will lead to skewed statistics over time.