I'm not debating the merits of centrists of either side, I'm talking about the extremists.

First, of course, it requires someone to concede that groups like the Nazis and Italian fascists were on the "right", which is in and of itself disputable. Reactionary movements like monarchists can certainly be called groups on the "right", but when Mussolini said "tutto nello Stato, niente al di fuori dello Stato, nulla contra lo Stato", it doesn't sound like anyone on the Right. The same applies to the Nazi anthem, which honors the memory of "Kam'raden die Rotfront und Reaktion erschossen", meaning shot by both the communists and conservatives.

But if we assume, arguendo, that militaristic states are "Right" when the communist states are "Left", we see that the Left is still worse than the (putative) "Right". Yes, they all shed blood of opponents. But for the average person in Franco's Spain, or Mussolini's Italy, or Salazar's Portugal, or Pinochet's Chile, or dozens of other similar regimes, life was tolerable. Not one of those countries suffered famines, not one of those countries saw entire families being punished for anti-regime activities of one of that family's members. There was some repression, but life went on, people owned what they owned before the dictator came to power and they generally all had freedom of worship, freedom of enterprise and the freedom to travel.

Not so with the socialists. Famines, shortages of essential materials and power blackouts are endemic to socialist states. Infrastructure slowly crumbles. Safety is ignored (cf. Chernobyl and environmental pollution on a massive scale). Ongoing repression hits regime opponents and their families. Religion is abolished, private property is severely restricted, travel overseas, when not banned outright, is strictly controlled and family members are held as hostages to keep people from fleeing the "workers' paradise". And the repression never ended because the socialist experiment never ended. Thankfully, the Soviet version collapsed, but the North Korean and Cuban versions remain, sending people to forced labor camps for their crimes or the crimes of family members, propped up by China, which itself maintains the repression while not the economy of the socialist states.

Nazi Germany was certainly terrible, but when we look at the history, it was the exception, not the rule, for ostensibly "Right" extremists. The rule was fairly banal and mundane. There are no exceptions, however, on the Left extreme, that were measured and restrained in their repression or the misery they caused. Not one.

Then Bernie says he means "Denmark, not Cuba" (now, though certainly in the 1980s he meant Cuba). This is dangerous for a whole host of reasons. First, of course, Scandinavian countries coasted on the fumes of earlier entrepreneurial periods in their development when they instituted an expensive and expansive social net, the cultural homogeneity and mores of the society (Jante law) meant that the system wasn't abused (at least initially - attitudes are changing dramatically), they kept a free enterprise system, and EVEN THEN it has been failing, leading to reforms to scale it back. As Ayn Rand pointed out, they ran out of other people's money.

Also, so much of Twentieth Century politics was shaped by the Cold War and US and European anti-communism. It forced socialist parties to abandon their extreme claims because they were suspected of being stooges of Moscow, and communist parties that were openly so were associated with the revelations regarding the Terror in the 1930s following Khrushchev's 1956 "secret" (i.e., openly disseminated) speech admitting to mass executions under Stalin. The loss of prestige was enormous, and even the sex appeal that the Left found in revolutionaries like Che Guevara or Ho Chi Minh couldn't really save extreme parties in a Cold War environment. As a result, socialist parties jettisoned the "nationalization of the means of production" (the CENTRAL tenet of socialism) from their platforms and started quietly rebranding themselves as social democrats. That, however, is changing again, as general amnesia hits everyone. Look at Labour in the UK - Corbyn went hard socialist (and, thank God, lost because of it). Other parties are moving farther left, and the ones that aren't (like the SPD in Germany) are dying on the vine.

Bernie is just the icebreaker for this sort of radicalism.

Worse, however, is the fact that because the modern definition of "socialism" is being confused with "social democracy", as people start to vote for "socialists" they won't ever know exactly what they're getting, and the demands for ideological purity will force them in ever more radical directions. As you're well aware, it was incredibly fashionable in educated and noble circles in Russia in the early Twentieth Century to be a "socialist", by which most people thought they meant measured social democracy, Bernstein-style revisionism and a point at which the whole experiment would slow down. But that's not how socialism works. You can't get enough people to vote for more radical ideas, so the radicals eventually stop honoring votes anyway. YOU CAN SEE THIS ON THE LEFT IN THE US TODAY ALREADY - "abolish the Electoral College" (which would destroy the cohesion of the nation), "create hundreds of new voting districts to overturn Republican majorities", "create new states to pack the Senate", etc. This is all about breaking the system to force a particular result.

All the while, these same people who are against our voting system, free speech, religion of any sort, the right to bear arms and a whole host of other freedoms, are calling the people defending those rights "fascists". Fascists weren't on the Right, and they didn't defend those values. But even if, arguendo, the choice is between "Fascists" and socialists, I'll pick the former because in the worst case scenario I have at least an 80-90% chance of a normal life, and under socialists that chance goes to zero.

Thankfully, that choice isn't upon us. It's a choice between freedom and socialist fascism only.