If anyone knew the answer there would be no addicts.
In the end, their drive to sobriety must be consistently stronger than the drive for drugs. There’s no moral system with the power to counteract that. And it’s not a moral failure that they can’t.
In other contexts people love to blather about the power of discipline over motivation. Well this proves the lie. It has to come down to motivation, consistently. And you probably don’t have the power to motivate them to consistently stay sober. You can’t make sobriety consistently more enticing than getting high. The rest of us are more enamored by what sobriety offers. We are not morally stronger. We just prefer being sober, consistently (or some of us prefer other, less-destructive forms of intoxication).
Sorry about your friend. Take care of yourself.
You have more control over your attitude than over politics, or other peoples’ opinions. Don’t exhaust yourself and don’t strain your relationships uselessly. They want to bring you down and push you out. I usually reject stoicism, but this is a good time to be stoic and keep your energy reserves, and your attitude, fresh.