Part of it is selection bias, I would say. You think that most people who disagree with you are illogical, but you don't say anything about those who agree with you. Are they more logical than the average person? (If most people make terrible arguments, then it's probably the case that most people who disagree with you will make terrible arguments.)
Also,
Perhaps I am, myself, victim to some bias that I have not read about despite months on this site. Does anyone recognize it?
Part of it is selection bias, I would say. You think that most people who disagree with you are illogical, but you don't say anything about those who agree with you. Are they more logical than the average person? (If most people make terrible arguments, then it's probably the case that most people who disagree with you will make terrible arguments.)
Also,
The Dunning-Kruger Effect.