"It is really hard to support left-wing (in this case pseudo-left-wing) positions when their proponents make it sound like it's all just about resenting people who are successful, rich and powerful."

What makes it harder is that right-wingers PRETEND that "leftists" resent "people who are successful, rich and powerful." We say "too much wealth in the hands too few people is bad", and rightists say "You only say that because you resent the rich". No, we say it because it is historically demonstrated fact, and has been one of the cornerstones of political economics beginning with Adam Smith.

In the recent thread on Pope Francis and libertarianism, one libertarian was condemning the minimum wage, but did not object to excessive CEO salaries. His real objection was that the big bad government   established the minimum wage, and anything the government does  is automatically bad. But still, if he knew anything about economics, he would object to excessive pay at the top, not at the bottom