I respect your decision to not drink. I think it's a reasonable conclusion to have come to for yourself.
But I also understand why your argument doesn't go over well. You attempt to logically justify your decision, not to drink, but your argument isn't logical. It implies that there are exactly two cases in which people drink:
- They drink for courage, and you don't need any.
- They drink for fun, but don't drink responsibly, and so terrible things happen.
Have you never experienced a case where someone around you drank responsibly, because they wanted to, enjoyed it, and nothing bad happened? It's hard to believe. I did so the night before last.
I'm not suggesting that this fact should change your decision not to drink. I'm suggesting that, without recognizing it, you've constructed a flawed argument against anyone drinking. It's probably just an emotional response to the abuse you've taken for your decision, but it comes off as sort of smarmy.
You don't need an excuse or an argument not to drink. Personal preference. End of story.