On the contrary: most people in the world are ignorant, useless wastes of your time. One SHOULD cut them out of influencing you and taking up your attention. If you can choose to optimize yourself for interacting with the average mathematician or interacting with the average person, you should choose the mathematician.
But in any case: who said anything about cutting off? What exactly are you picturing here? Some sort of outfit that renders one invisible to anyone but bronies? That's not how clothing works, except in extreme examples.
But "people who should be ignored" and "people who don't care how you look" are hardly identical sets. If anything, they're more likely to be opposed than overlapping. The sort of people you want to deal with are usually those with enough merit to have choices in who they interact with, and thus they're naturally more picky.
This is a repository for major, life-altering mistakes that you or others have made. Detailed accounts of specific mistakes are welcome, and so are mentions of general classes of mistakes that people often make. If similar repositories already exist (inside or outside of LW), links are greatly appreciated.
The purpose of this repository is to collect information about serious misjudgements and mistakes in order to help people avoid similar mistakes. (I am posting this repository because I'm trying to conduct a premortem on my life and figure out what catastrophic risks may screw me over in the near or far future.)