You can’t force them to care but you can inform them about what tools they have at their disposal and how they might be releasing information to more people than they realize. For example, when you make a public social media post, everyone can see it, not just your friends, and it will stick around forever.
The most important thing is to get them to think about privacy in terms of a controlled release of information: how do you make sure only the people you want get the data you want them to get. A great example is E2EE messaging. Only the intended recipients can read the messages. Privacy isn’t about never releasing any information ever, it’s about having control over where your data goes. I think the misconception that you can’t have any data go anywhere or it’s not private has done a lot of damage and turns people off of privacy in general.