That's a nice false dichotomy you have there. Florida's average death rates in the US despite having a highly vulnerable elderly population prove that.
Of course vaccinated people can still get COVID. Everyone knows that. Why repeat it? The point is that covid becomes a very low risk to the vaccinated. Once vaccinated, you are more likely to die of the flu than of covid.
Most theoretical mask studies were done when we thought COVID was primarily spread by droplets, not aerosols. To this day I haven't seen any study plausibly show that others' masks protect you as much as your own mask. I'd be happy to be proven wrong if there's any real scientific evidence out there.