Then maybe people shouldn’t ask why if they don’t want to hear the answer. I think it’s a rude question to ask so I don’t really have any pity for someone who finds themselves bored with the response.
Being rude to people who are rude (especially in cases that they don't realize that they are being rude) generally sours relationships, unfortunately.
That depends more on how you say it. Try not to invoke guilt. After all, you presumably like these people and don't want to make them feel bad - but you just don't want to drink. Guilt is where it can go wrong, so you kind of have to dance around it.
I have found it’s generally quite easy to say “I don’t like the way it makes me feel”, which is relatively guilt-free. A less-strong one might be “I don’t like the taste”. It helps that it’s true in my particular case, of course.
Then that's rather pretty shitty of rest of us. The rest of us should just have someone's "No" and bugger off.
I happen to be excluded from your "we" ;) We would like it if people didn't do this, but it happens and it doesn't help us to be annoying. Especially in cases where people don't realize that they're prying being sanctimonious in response can come off as being unreasonably smug.