Don't put all your trust in a mentor on achieving your goals in life, it is because your mentor and you had different situation that has also a different solution, so i think we need to have faith in our own self capacity to pursue our dreams not just trusting our future to others or to mentors hand.
You are right halfway, what about those who "cannot" and "will never" discover themselves by themselves, let alone have faith? This is where mentorship comes in. Some of the successful people you see today were picked, motivated and helped in one way or another before they achieved success. Fine, it's not everybody that needs mentoring, but that should not silent the fact that many more people need it. And I tell you, had it been some older people who are poor today found the needed help of mentorship at the right time, it's highly possible they would not be poor. Don't also forget that it takes success to be a mentor and that alone is a plus to every mentee.