Schadenfreude should be occasionally amusing. Indeed, one of the most basic bits in comedy is when someone who’s too proud, too vain, or taking themselves too seriously, gets a comeuppance. But there’s a profound difference between the humor of a momentary discomfiture…versus the humor of yet another boot to the face. When someone set high is taken down a notch by humor, it humanizes them. When someone already cast down is mocked, it’s often adding to their dehumanization.
If your entire sense of humor is “somebody else is uncomfortable” then it’s a signpost that maybe you’re a dick. And when the “joke” is its funny because group of people X should suffer you’re crossing into wingnut humor.