"knowing you as well as I do"

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!

Solution 1:

While "as well as" can mean "in addition to", in this case it just doesn't.

Here, it means "equally well" or "well to the same extent as", just like "as tall as" means equally tall or tall to the same extent.

Here, "I do" means "the way I know you". Just like, "Nobody eats shrimp like I do" means "nobody eats shrimp the way I eat shrimp".

Putting it together, "knowing you as well as I do" means "knowing you well to the same extent that I know you well".