The salient point, IMO, has nothing to do with “sleeping easier”; rather, it’s that MNTA call-writers are not viewing forgone upside as a bona fide economic loss.
I would suggest that that is just a possible explanation of WHY they sleep better at night when writing calls. Different people put different psychological importance on lost opportunity vs lessened downside vs ... .
FWIW - Some years ago I heard someone opine that a crash is when everyone is thinking the same way (e.g. same time horizon, same worries). What makes the market stable is the large number of different philosophies.