Talk to an old biker and he may swear that CO2 is good for you.
Have you ever seen someone get defensive at the mere mention of a topic? Eg. that the planet is over-populated and that reducing the population is one of the best things we can do to save ourselves? Well, some immediately enter solution-mode and they talk as if you are arguing for gas chambers (or something equally idiotic).
It's quite draining to talk to people when you know their worldview does not allow a conversation about something. But it's also important to understand how it happens, and that you cannot do anything. Now I wish I could find that lecture, but I couldn't. Finding these gems amidst all the junk on the Internet is a challenge.