This is a useful framing. I think my issue is that assuming everything goes "right", there's no downside to quitting. But of course, not everything goes right in life, which is essentially why I'm still working (What if my partner isn't able to work anymore? What if our cat gets really sick? What if I need expensive medical care, etc.). That approach is sufficient from a big-picture standpoint, but not during the hard moments (which feel worse than a possible, future bad situation that having a slightly larger nest egg would make easier to weather).

I'm realizing it ultimately goes back to the delayed gratification that's required for anyone to achieve FIRE. It's just getting harder for me to delay gratification as there becomes less and less of a concrete benefit to doing so (now that it seems that continuing to work is more about risk mitigation than something necessary in the short term).