Obviously I'm just theorizing from my armchair and don't know more than you about this, or want to be agreed with, it's just that your post sparked my interest and I'd like to know more because my hunch is that removing excuses to not change oneself is generally a reasonable thing to do, even if it can hurt in the short term. In fact, it kind of worked for me to improve myself in the past (not regarding intelligence or academic/professional achievements, but other aspects of life). Maybe it depends on the particular person and situation?
It' might've helped things looking forward, but looking backward I think it wasn't great. As in, "I am so smart and yet thus far have accomplished nothing." So, maybe that's a debt to be paid, and once paid a person is able to move forward at a better trajectory than before? That might make sense to me.
What was the lesson you learned specifically from this?
You're aware of your flaws because they're a part of you, but that doesn't mean that anyone else notices them.
Thought this was just me...
We talked a lot about how literally no one on earth is capable of seeing an understanding your flaws as well as you, but also most humans on earth are infinitely less interested. The lens you view yourself with is totally unrelated to the lens with which the rest of the world sees you; you'll drive yourself insane if you think you and the world interpret you the same.
The point is, I think he did a phenomenal job at blasting my self deprecating brain into reality, but his initial spin of "Stop treating yourself like you're an idiot, because you're not and I can prove it" was just a slight misstep.