It's less that they "get off on" suffering (though I'm sure some do) and more that they believe some conclusions:

1. The universe simply does not permit an arrangement of humans that isn't a hierarchy of exploitation and suffering.

2. There is a "natural" hierarchy which is also a just one, where good people deserve to exploit and bad people deserve to suffer, and of course I'm not one of the bad people. ("Just-world fallacy.")

3. Anyone who says don't need to build a Torment Nexus for anyone is a sneaky liar trying to trick their way upwards into a layer in the hierarchy they don't "deserve."

So it's not as simple as sadism or greed, they'll tolerate some being stepped-on as long as they've been convinced that the "right people" doing the stepping and the bad people are getting stepped on more.

A relevant free ebook from 2006: https://theauthoritarians.org

Sure but there is some sort of grayscale.