I see that perspective and appreciate the comment. To be more clear, the weird thing to me is the __degree__ of fanaticism. I understand being passionate, there are many things I'm passionate about. But there are very few things where I would drop everything and campaign for someone. This REALLY reminds me of religion (I left a religion that sends people to go knock on peoples' doors for 2 years of their lives).
I also think politics (I'm not sure if it has always been that way, but I don't remember it like this when I was younger) has a lot of parallels to religion and that similarity is growing. I do actually believe this is rooted in the growing partisanship. That political answers are not "best solution vs a different solution" but "good vs evil". Partisanism relies on good vs evil. There's a John Cleese skit about extremism that always makes me laugh[0].
To take the religion + politics thing further, consider that the president is hailed as being sent by God, and is surrounded by Christian Dominionists that are actively trying to apply make the U.S. a theocracy.
That's bound to stir up some passion on both sides, being that the stakes are rather high.
One key thought experiment I like to do is to project out a behavior pattern for all people and then asking whether that would be a positive or negative for yourself and society. If everyone were to campaign and push for the ideas they care about, I do believe that would result in a more informed and better society. Through the marketplace of ideas, we can fight through the differences and hopefully create better policy and have better leaders execute on our future.
I think for a lot of people, taking action to affect change for the community/society you live in is very natural. On a small scale that can be something like running for class president or joining your HOA. At a larger scale, politics is where change happens.
If you believe in a set of principles, it is sometimes worth your personal time, effort, and money to affect change. Hopefully you can see that from their perspective they are about their own future and this is the most effective way to impact that prospective future.