NAZIs were not socialists. They just co-opted the word.
>Nazism rejected the Marxist concept of class conflict, opposed cosmopolitan internationalism and sought to convince all parts of the new German society to subordinate their personal interests to the "common good" and accept political interests as the main priority of economic organization.
https://en.wikipedia.org/wiki/Nazism
Take a look at Sweden when their policies were more Socialist skewed, the government in order to manage the P/L sheet for social welfare programs compelled political out groups to be sterilized[1]. Roma people were considered a "drain" on Swedish society and attempts to exterminate them were done much more quietly.
If any government starts to make value judgements about who is more valuable than whom, they will repeat these same errors.
[1]https://en.wikipedia.org/wiki/Compulsory_sterilisation_in_Sw...
This point is _unusual_ in Swedish 20th century history as a time when the socialists where _not_ ruling by them self but instead ruled in coalition with the right wing. The minister of justice was for example _not_ socialist.
https://en.wikipedia.org/wiki/Hansson_III_Cabinet
And the peak, some where around 1500 sterilizations a year, for eugenic reasons (if I read your diagram correctly) is _damn ugly_, but it is not extermination. It does not compare to Soviet, Chinese or American killing of their own populations (which is hard to call exterminations either even if we are talking about millions; genocide I guess is better term).
Ugly things happens in socialist democratic countries like Sweden. In general they get much uglier in powerful communist (Soviet, China) or powerful right wing countries (USA). The killing of native Indians in America by non-socialists is strikingly bad for your argument.
Kind of why McCain used the word in a negative manner this week.