I appreciate you taking the time to write this article, but you haven’t really answered the premise in the title. I think the biggest part of impostor syndrome is the fact that it makes you doubt yourself which drains you of energy and bullies you into hugging your comfort zone. And sure, learning and improving yourself and being truthful to others about the fact that yes, you’re not perfect might help improve the circumstances, but they don’t address how you feel about yourself.
I think the best way to deal with it is to have a conversation with yourself in which you confirm, in an adult and balanced manner, that you are enough and that you are ok. That doesn’t mean you should stop learning, only that what you do know is awesome and there are so many people who would find what you’ve already accomplished so difficult to even pick up. And the way you’ve gotten this far is the way you’ll continue to grow. Sure, some people will have expectations, and those expectations might block your entry into some fields, but that’s fine, life doesn’t have to be a series of perfect choices and unmissed opportunities.