Only answer their questions when they ask.
It's more effective by not saying anything.
Then when an issue comes up for them, they say, "hey did you hear about this story or that story, whats up with that?"
That's how it starts.
Eventually the things you tell them actually happen and come out in the news.
They are more to believe what you're saying because of that.
If they're really you're friends they will stick around regardless of what you say.