I used to call people stupid an awful lot, in my head, and I didn't like myself much for it. I did it because I kept getting a strong feeling of surprise when they didn't seem to grasp the "obvious." Once I've got used to an idea or discovered a fact, for some reason it's not long before I see it as dead easy, as something that only an idiot wouldn't know.
My job as a lab technician was probably quite complicated, but I always saw it as being little more than a skivvy's job with a bit of scientific window-dressing, and the only hard thing I felt there was about it was working out how to work quickly enough to finish by the end of the working day. That always was hard for me, and I'd used a lot of ingenuity to gradually make it quicker, so I felt it was no disgrace if others couldn't match my speed for a while. So I would have been surprised if another person had any trouble with my job apart from the pace. I had a job drying herbs once, and I felt my results were pretty mediocre (the colour tended to be a little faded and the aroma was weaker after the drying process), until I saw examples of herbs that other firms had dried. I just couldn't understand how they'd managed to get such a lousy result.
I think I was so used to (and unaware of) being extremely thorough and perfectionist that I tended to think anybody who delivered "90% of the result for 10% of the effort" as being too thick and lazy to go that final mile for a first class result.
I think mind-blindness comes into it. Just like with interests - if I'm fascinated by a thing, it feels as if nobody in their right mind could fail to see the attraction, that most other people are silly to be so interested in boring things when they should be interested in interesting things.
I've mellowed a lot, and I can now see there's a bigger picture than just the one task, and that what seems to me a blindingly obvious fact that should have been learned in kindergarten can be completely new to a person with a different history, and that it's no reflection on their capabilities if nobody's told them about it yet. I also appreciate that I may be uncommonly able in some ways, so the argument "I can do it, I'm not particularly smart, so if you can't, you must be rather stupid" no longer makes much sense. It's ironic that low self-esteem led me to look down on others via that argument, and that seeing myself as "smarter-than-the-average-bear" (which might be thought arrogant) improved my respect for the abilities of others.
I also used to play God a lot, seeing the futility of war and all. Couldn't see why the masses were so tunnel-visioned. I was on Captain Nemo's side. The reason, I guess, was that I wasn't under attack myself. When you're attacked, you realise that you're not God, you climb out of your ivory tower, you stop envisaging perfect societies and you fight back.