The thing about trying to persuade people is most of the time it doesn't come from the right place and both sides just dig in and resist the other point of view. We get really attached to our POV, why, I remember back in grade school, I think in the second grade we had a text book that erroneously said Abraham Lincoln was Democrat, I really admired Abraham Lincoln so I started to identify with being a Democrat to whatever extent a 7 or 8 year old could.
The next year in the next grade we had a text book that rightly identified Lincoln as the first Republican president and I was so angry about this I remember complaining to my mom, although I don't remember exactly how I voiced my complaint but by then I felt I was a Democrat and this new information just made me angry, how could they say Lincoln was a Republican? How could there be such a huge difference between the 2nd and 3rd grade?
By that time it didn't even matter what the factual information was because I had taken a position and I felt obliged to defend it. It was somebody else's fault.
But eventually I grew up and it wasn't by being persuaded by somebody telling me I was wrong, it had to do more with me questioning my assumptions and paying more attention to what actually appeared to be going on in the world.
So, if you aren't really good at getting people to ask introspective questions of what they assume you can just state the things that are indisputably factual and leave it at that.
The reason you noted that some college students seemed dumb is because they aren't engaged in learning but in indoctrination. People who are raised like your friend are indoctrinated and no matter how intelligent they are, because they haven't questioned their assumptions and actually owned some knowledge they are susceptible to every sort of con artist. South Park nailed that type of person as a college-know-it-all hippie.