I don't acknowledge when people sneeze and it makes them uncomfortable.
That's pretty cold. Why don't you acknowledge when they sneeze?
I feel the social convention of acknowledgement is dumb and humiliating
It's rude not to bless someone when they sneeze. It doesn't take much so why make people feel uncomfortable about it?
Fuck them and their throats.
That is getting pretty aggressive over something so simple as just saying bless you. It's just a small thing to do and won't hurt you to say it.