Just because people don't seem to care, doesn't mean they aren't listening. Even being "that guy" who makes a point about important issues without obvious agreers can have a positive affect on people. Think of it like advertising: you might not buy that shiny car now, but when you go to make a decision, all those car ads you consciously or subconsciously watched make you aware of their existence. When the time comes and people have to make decisions, many might bias towards your point of view. Don't nag, but quietly continue making the point. Stay positive