Never thought of self-importance as a defense mechanism. Perhaps I’m just used to filing them wholesale under the “narcissist” category and relegating them to the part of my mind for people who are just too shitty to be a)trusted or b)viewed as fully human.
I do have to admit that there are people who are notoriously self-important that are in my life despite my best efforts. I would happily drift back to stranger status with them but I am friends with people they very much want to use in their own social status climbing efforts. This means I am often dragged in on conversation just because it seems like a good idea to work me to maintain access to the people with more power than I have. (I am mainly in those particular “power” friendships for the laughs and story swapping.)
I have seen the horrendously self-important punctured from time to time. They’re sick, or had a fight with a girlfriend, or something. In those moments, I find those people tolerable… even likable. Those moments are rare. I also think there’s a problem when I can only really like a person when s/he is at his/her lowest. Sometimes I think it’s a failure of my own character. But when I think about how those relationships have turned out over time, I recognize that this tick is a function of my character. It helps me recognize a more subtle crazymaker.
Besides, if someone has their defenses up that high, it’s just not my job to scale them. I’ll just go toward the people genuinely willing to let me in.