I have been mentoring young business owners for almost 6 years while always continuing to learn more myself. I find it a bit strange that the more I learn, the less qualified I feel to mentor others.
The startup industry is complex and developing at a very fast pace. There is no way for anybody to keep track of everything that is going on, let alone know how everything works. I have realized that, and I have also realized the importance of finding the right people to work with, as that is the only way to make up for our own limitations.
Even though my knowledge is limited in many areas, I will still continue mentoring and helping other entrepreneurs because I feel it is important to help others, even if they might just be a bit earlier in the process than you are yourself.
Nobody can be an expert in startups, but all of us have some knowledge or experiences that might help others.