Everyone's being so despondent. Of course it's possible to convince someone to care about privacy. If they're your friends, you'll know them better than we do. What do they value? What do they care about?
In my experience more people care about privacy than you think. But they just think it's hopeless. They're constantly being told "There's no point. Every company already knows everything about you. Give up."
Bullshit. Even if ad companies have a nice tailored set of data on someone's interests, behaviours, routines, etc. the moment that person cuts off the supply, that data starts becoming less relevant, less useful and less valuable every day. Once I explained that to a few people I had a bit more luck getting them to install ad blockers and stop posting so much personal info online
Talk to them in a language they'll understand. If they deal drugs, tell them they're much less likely to get caught using encrypted messaging apps. If they're into true crime, point out how many stalkers were able to track their victims down using what they'd posted on social media