They don't see it, but it is very real.

While the extreme left and the extreme right do resemble each other in intensity of rhetoric and scrupulousness (and both have been in power to prove it), they still hate each other's guts. They may throw rocks at the same people from time to time, but they turn on each other like rabid dogs if given the chance. Ribbentrop and Molotov were toasting each other in 1939, at war with each other two years later.

..and sincere push for Medicare for all, fair minimum wage, green new deal type legislation, and to pay for it raising top marginal tax rates and expanding the estate tax.