I think the general idea of those against it is that they assume it is zero sum. Meaning, for everyone to be taken care of, the person must lose or have less.

That still doesn't make sense for people who aren't billionaires, though ... if it's zero sum, billionaires are even more problematic than they already are.

As Ronald Wright said , A Short History of Progress (2004): "John Steinbeck once said that socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires." (note, John Steinbeck never said that)