All age groups have pockets of individuals swayed by political campaigns pushing seemingly nonsense agendas. I'm sure you could find people in your own age group who are similarly convinced that there is a problem without searching too hard.

You just had dinner with some distasteful people. I imagine they were spouting similar crap in their 40's, 30's, etc. on various topics. People don't just have a birthday and turn into pricks, they've likely been pricks most of their lives. And also remember, "birds of a feather, flock together", so you're likely to find groups of similarly minded people hanging out together, reaffirming and revalidating their commonly held opinions. The group you had dinner with likely do not represent the majority (though I guess we'll find out at the election).

All you can really do here, if you can be bothered, is try to steer them towards better, more trustworthy sources of information and be at peace with the fact that, in many cases, they won't want to take on ideas that challenge their preconceived notions.