This is a rather amazing claim, I would be very interested in seeing some supporting evidence, since alt-right has far more in common with the left than with any proper and traditional conservatism. Unless, of course, you define "people I don't agree with" as alt-right with no regard for what they ideology might actually be.
If there are conservatives that don't engage with the world like this, I want to get a drink with them, on me, because I've lost hope.
I'm very curious what ties you see between the alt right and the left. I don't define the alt right as "people I disagree with." There's plenty on the left I disagree with - anybody engaged in violence, for starters.
People at The American Conservative [0] might be religious nuts but I don't think anyone could in good conscience accuse them of being anywhere near alt-right.
And alt-right engages in identity politics, believes in primacy of the group over individual, see "enemies" behind every tree, and want to use the State against groups they dislike. Very much like the left. And while you would not want to meet either on a dark street, both, in US at least, are, generally, clowns who would be the first ones to be sent to the camps in the Reich, or USSR, or any other shining example of what happens when either come to power.
Political rhetoric has always been inflamed. I see it from my liberal west coast politicians. I see it from friends and family. You yourself have said that all conservatives are alt-right.
> If there are conservatives that don't engage with the world like this, I want to get a drink with them, on me, because I've lost hope.
The truth, I suspect, is that they are probably all around you. Most people are not particularly introspective or philosophical when it comes to politics, but if you dig in you'll generally find there are good reasons for them believing the way they do (even if, in the end, you find those reasons unconvincing).
Dr. Haidt has done reasonable job (as a liberal) of trying to understand the conservative mind. I also recommend Arnold Kling, an economist who wrote The Three Languages of Politics, and Thomas Sowell, who wrote A Conflict of Visions.
I should also add that there is an increased intensity with some of the rhetoric, but I think that has more to do with people (on both sides) sensing that we may be undergoing a shift in the political landscape, and that more is at stake than usual. If so, it's not the first time it's happened in U.S. history (they happen approximately every ~40 years, from what I've read). Hopefully it will pass in a few years, but we'll see.