I think a big reason for polarization is that it has been monetized. I've read that studies show that the more riled up an article/post/news story makes you, the more likely you are to click on it, read it or watch it.
I have read that on the internet, the sites and platforms know this, and their algorithms automatically feed you more stuff that riles you up so that you watch/read more riling up stuff. On TV, talking heads that rile us up generate more eyeballs on screen which generates more revenue for the broadcaster.
And people are predisposed to believe, quite sincerely, what they want to believe, and much of, probably most of, what we believe is based on what we are told, what our environment is, i.e., what our conditioning is.
This is just the way the human mind works.
Like everyone else, I don't know what the fix is. But one thing that would surely help is more civility. While on this forum we have divergent views, we are, by and large — and with some help from the big griller and his deputies — civil to one another.
I think the civility of this forum has much to do with its popularity.
Yet, even here, where we are civil to one another or we are not permitted to participate, politics is simply out of bounds. Too polarizing, two volatile, to even attempt to discuss civilly.
A sad state of affairs for our country and for all of us, to be sure...