Vaccines do not provide an energy shield around you to block viruses. It just trains your immune system beforehand. Less severity of symptoms, less chance of hospitalization, less chance of death. Testing positive means little, as Omicron spreads so much everyone is gonna be exposed to it at some point. Omicron's decreased lethality + vaccination means they have nothing to worry about.
If that's not enough, you can see people proudly boasting of not being vaccinated, then dying of the very virus.
https://old.reddit.com/r/HermanCainAward/