Imposter Syndrome, which I’m using loose and not using to its clinical definition, is the feeling that a person is not actually competent at a job which they are manifestly competent at. I think that for many people it stems from being overly impressed with other people, putting those others on a pedestal, and not realizing that everybody everywhere is just “winging it”. That is, doing their best without full knowledge of what they should be doing. That is in fact the human condition—we are finite creatures and must live life by trust—but some people seem unable to accept that and have the conviction that other people must know what they’re doing. Only God knows what he’s doing; he’s the only one who accomplishes all things according to the intentions of his will. But for those who can’t accept that, they must turn others—often kicking and screaming—into God-substitutes and pretend that these people really know what they’re doing. (It’s part of the reason people turn so quickly and viciously on their idols—they view imperfect as treason, since they’ve elevated their idols to the status of God.)
Another coping mechanism which the sufferers of imposter syndrome have is to try to turn life into something they’re actually good at in this sense that no human being can be good at it. Thus they come up with a myriad of byzantine and difficult but achievable rules, then need to have everything in life go according to those rules in order to “feel in control”. These rules tend to cluster around anything with an inherently high degree of flexibility, such as around social interaction, writing fiction, etc. “When you visit someone, you must bring a food item” is really more of a ritual, being such a common rule, but it’s a way of showing that one cares and is not merely mooching. Especially in the modern world where food is absurdly available there’s little benefit to it, and so far as I know it was never the custom among rich people, but it gives something to do such that if one has done it, one did a good a good job and is not open to criticism. This is such a rule which caught on (and I’m forced to use a rule which is not particular to an individual in order that it might be generally recognizable), but they abound. Some people must always check the stove before leaving the house, some people must always hand-write thank-you notes, or send thank-you notes on paper rather than by email. An alternative way of thinking of these things is as ad-hoc superstitions.