Before the trade, you run the film: the move happening without you, the chat room celebrating, the screenshot you will have to see. That imagined feeling is what drives most fomo entries, not any analysis.
The film is unbalanced. It is easy to picture the move you missed and hard to picture the equally likely version where you entered late and got stopped. Anticipated regret shows you only one branch.
Playing the other branch out loud helps. So does a rule that says any entry more than a defined distance beyond the trigger is skipped by default, which converts a live emotional decision into a settled one.
Related: regret-aversion, fomo