The situation is that one of my friend's roommates took part in a test of narcissism and got a score of 14. My friend wanted to get in a dig at that guy, so he said"Well, knowing you as well as I do, a score of 14 must be near the top of the scale."
My question is, what does"knowing you as well as I do" mean here? I only know that "as well as" means "too", so it's a bit awkward here for me to understand. Many thanks!