“Everyone's already made money on this or gotten in on this deal — I'm going to miss it.”
What's happening
Watching other people gain from something you're not part of creates urgency that has nothing to do with whether the opportunity is actually good for you — it's a reaction to being left out, not an evaluation of the decision itself.
A financial example
A coworker mentions doubling their money on a stock everyone's talking about. Buying in now, after the run-up, based on that story means reacting to someone else's timing and someone else's risk tolerance — not your own plan.
A better question
Would I still want this if no one else were talking about it?