I've always felt a bit of imposter syndrome at work. It doesn't help that my boss is an "everything is disappointing and frustrating" guy during the year. (Even though at the end of the year they always end up paying me a bonus and telling me how much they appreciate my work. Go figure?)
I don't know if my feelings of never being quite "enough" are exclusively the result of inceldom, or if they are just part of the whole puzzle.
I never used to pee in public urinals until my 30s. I know how ridiculous this sounds, but in my teens and 20s I was always worried about some high school tier shit happening, l.e. "OMG look at this guy's small cock! You can tell he's never fucked!"