You are absolutely right, having a mentor isn't a criteria for success, you can become very successful without having a role model or any one you look up to. Achieving success is all about dedication and consistency to you goals and ambitions. As a matter of fact having a mentor without having a drive or prospect would take you no where. Some people are of the opinion that having a mentor isn't necessary and believing in yourself and working hard is the only thing that matters, it's not entirely correct but it actually makes a lot of sense.
This is true about those successful people that I know, they have become successful even without any mentor at all. What inspired them is the battle of life and that means that they can stand on their own.
But for them to scale up, they need someone to help them for their business to grow and I think that's where the mentors can get in. They've given them some tips and help on how to increase and upgrade their businesses.
There are things that we cannot do alone even if we're successful, we did it on our own but when we want to have something for our business to expand, we need help from the others.