It seems to me that American leftists like to proclaim that they love America; but what they really love is some romanticized view of the America that they visualize, rather than the America that actually exists.
Hence, as long as they can get their own way, they remain relatively quiet; but once that is challenged, they rise up in furious revolt!
Is it very hard, then, to see why some of us would view them as being closer to Marxist revolutionaries than to American liberals of the past?