An often glossed over reason being vaccinated and why it mattered, was so that when a person was infected, apart from the hope the infection wasn't as severe but the virus had less time to undergo a recombination with other viral segments which could lead to a new more dangerous strain. Ultimately to a few people, days, or even hours might not account for very much, but the sum of hours is quite significant, for thousands or millions of people.

Unfortunately the slow roll out of vaccines and various govts resisting locking down, meant that new more dangerous strains were an inevitability.

From what I recall, it was the arrival of Delta where, even if vaccinated, the accumulation of infective covid virus in the nasal passages was about the same. Don't quote me though it's well over a year since I was reading such material regularly. However the time the virus had to play in a host human body was still less than the typical unvaccinated person. That's why a lot of "seemingly pointless" incentives were put in place by various govts around the world, those who could get vaccinated, would be moved to do so. Sadly people who could not on medical grounds often did get caught up in the details.

People who still wear n95 masks clearly don't want to get the virus, it's not a mental condition. They're most likely around loved ones who are vulnerable.

Those people might be sick (either with covid/the flu/cold etc) and using the mask as a signal to others "please don't come near me I'm sick".