Everyone who uses their voting power (10 votes per day) earns the same curation rewards, except for being downvoted or late votes (after 24 hours).
This didn't used to be the case, but now all you get for curation rewards is a mostly-fixed ROI for participating in using your stake to direct where rewards go rather than being completely passive.
RE: The main excuse for malicious down-voting is "Over-Rewarded Content..." What about the account making $10k+ PER DAY in spam comments?