Cheesy1
IMO it’s a kind of coping strategy for having made a mistake (getting circumcised) that cannot be reversed.
The human mind can’t accept that, so it seeks validation. Denial of the obvious (I don’t miss any sensations!) is one symptom; encouraging others to follow (DM me for more details!) is another.
A forum like this is full of non-circumcised males, most of them American and vulnerable to concerns about not being circumcised. It’s a target-rich environment for seeking more converts, and more validation.