@MsRinky I think you’re spot on. I’m teetotal too and I don’t like to tell anyone because I think it makes people annoyed just to hear it. I think you’re right that people dislike those who they think think they’re “better”, even though I don’t think I’m better in any way on either front and in relation to alcohol am really not bothered if others drink or not.
It can also go the other way where it comes out you’re vegan, you’ve said nothing about it and people start protesting “oh I don’t eat much meat.” Or it comes out that I’ve stopped drinking and they go “oh I’m trying to cut back myself” or “I only had a small wine at the weekend, I needed it, it had been a hard week.” This is unprompted, I’m never asking people to justify themselves but they seem to feel the need.