Earlier quoted context omitted.
They might not want the truth now, but they could be shown why it's good to want it, and shown how much nicer that lifestyle is, and helped to change. Hard but certainly possible.
This lifestyle is nicer FOR YOU. Not necessarily FOR THEM. If I like spinach and you don't, how will you show me, that not eating spinach is nicer? Or the other way around?
As far as we know, the truth about eating is a lot more like "eat foods you like" than "eat foods X, Y, and Z but not A, B, or C". So we can all agree that I will eat spinach because I like it, and you won't because you don't. That doesn't contradict, and is no reason for disagreement.