I sometimes have a similar experience, and when I do, it is almost always simply an effect of my own standards of competence being higher than those around me. Imagine, some sort of problem arises in the presence of a small group. The members of that group look at each other, and whoever signals the most confidence gets first crack at the problem. But this more-confident person then does not reveal any knowledge or skill that the others do not possess, because said confidence was entirely do to higher willingness to potentially make the problem worse through trial and error. So, in this scenario, feeling less competent does not mean you are less competent; it means you are more risk-adverse. Do you have a generalized paralyzing fear of making the problem worse? If so, welcome to the club. If not, nevermind.

I personally am a fan of talking therapy. If you are thinking something is worth asking a therapist about, it is worth asking a therapist about. But beyond the generalities, thinking you are not good enough is absolutely right in the targets of the kinds of things it can be helpful to discuss with a therapist. Consider the propositions: 1) everyone is more competent than you at everything and 2) you can carry on a coherent conversation on lesswrong I am pretty sure that these are mutually exclusive propositions. I'm pretty sure just from reading some of your comments that you are more competent than plenty of other people at a reasonable range of intellectual pursuits. Anything you can talk to a therapist about you can talk to your friends about. Do they think you are less competent than everybody else? They might point out to you in a discussion some fairly obvious evidence for or against this proposition that you are overlooking.