Example: If you want more money, ask for it. If they refuse, it isn't "because of the money they're wasting on this guy", it's because they don't perceive your value as justifying it. That perception may be right or wrong, but it is what it is.
You're getting paid, you're doing your work (presumably), this other person and their actions (or lack thereof) are really irrelevant to you unless they are somehow having a direct impact on your work. IF they are making commitments to do certain things and then failing to deliver AND that in turn is making you look bad, THEN it might make sense to call this out to management; IF you can document the situation.
More likely, if it is directly impacting you, or your innate desire for "fairness" is piqued that strongly, the thing to do would be to just leave and go work somewhere else with better management.