Bottom line: you need a net worth of several million dollars to retire in Naples. It may be a very nice place, but for this kind of moeny, I'd much prefer retiring to southern CA because the climate is so much better than in FL. (I lived in both places so I know) and there are mountains, whereas FL is a pancake. The only thing that makes me thing twice about retiring to CA is the far left politics with all its terrible consequences on the quality of life. Hopefully FL will not turn woke/communist any time soon, but even that is not guaranteed IMHO.
Naples is definitely not inexpensive to live. The beach however is much much friendlier than CA beaches. And our taxes are considerably lower overall than CA with no state income tax etc. But SOCAL is lovely as well!!