It matters a lot to me, if there are a lot of unvaccinated, unmasked people in close proximity. I would not relish a breakthrough infection and positive test resulting in required quarantine (maybe at your own expense if you couldn't or didn't find trip insurance for that) or to be denied entry or exit based on a test result.

Certain demographics especially in their 50's and up, have actually been pretty sick, even if they didn't die.

There was reported to be quite an outbreak on a recent MSC Virtuosa Cruise out of Britain, including at least one death of a vaccinated passenger. Supposedly they had slacked off on enforcing COVID protocols. Most of this is self reported by the passengers since the cruise lines are not obligated and don't reveal that information.