That's because you don't realize that the only difference between the Antifa people brutally beating an elderly man or cracking someones skull with a bicycle lock and Nazi behavior in WWII is only a difference in magnitude, not a difference in kind.
Antifa is the Freikorps, Brown Shirts, SA (precursor to the SS) all rolled up into one motley group.
They’re a quasi-military group supporting a totalitarian form of government that eliminates rivals through violence, intimidation and, eventually, murder.
They’re more than a crazy bunch of kids.