Abusing anyone is wrong. Do note that saying "(majority group) (does/believes) (bad thing)!" is not abusive, however.
The problem isn't the mere existence of rich people who are bad; it's that economic systems of oppression exists because of the efforts of rich people who are bad (and the other rich people who don't act in resistance to those bad actors). If the majority of rich people favored measures of equality, a statement like "rich people are bigoted" would be nonsensical. The statement only matters to the extent that rich people's choices (both personal and political) affect the rest of society. This definitely doesn't mean that all rich people are bigoted/etc.
It's also not equivalent to "all (minority group) people are (offensive label)" because of social power dynamics. "All (minority group) people are (offensive label)" is damaging to the extent that (minority group) exists in a state of marginalization—if a white person goes to a country where white people are not the political majority, that isn't the same as if they go to a country where they are actively oppressed (if any such country exists). The weight such a statement carries depends entirely on its social context.
I understand why some people find generalizations about groups of people distasteful without regard for whether those groups are privileged/oppressed, but to the extent that language is a social action, when we're considering the effects of our language, that distinction is actually relevant.
This may come down to something like a difference in moral reasoning—person A might prefer to prioritize a rule (e.g., "don't generalize") whereas person B might prefer to prioritize consequences (e.g., "don't cause harm," which might only discourage generalizations which cause harm).
It most certainly does not. Noting the existence of power differentials and the consequences of those disparities does not in any way condone mistreatment of those who belong to privileged groups.
.
