Its sad but its true. The people on the fringes of the political spectrum have more in common than they do in ideological differences. They are:
Both incredibly anti-science
Both are increasingly relying on "feelings" over logic
Neither group is capable of holding a nuanced opinion. It's either full blown Soviet style socialism, or 1930s German nationalism
Probably worst of all, both groups have a fundamental belief that democracy is something to be subverted and ultimately destroyed. You see it with the actions of the GOP, but also with the way Bernie bros have manufactured a "scandal" in an effort to debase the democratically chosen party leader.