There will always be ways to abuse the system, it is just way too easy right now. They could at least attempt to implement a system to make it difficult.
Rewards need exponentially more voting to increase rewards beyond certain thresholds.
Whale accounts can not longer only upvote a single account and that is it. Make it so one single account cannot contribute more than 5-10% to the reward payout. These whale accounts also need to contribute to other accounts, so make it so they can only vote for a single account once a day, 3 times a week.
have large payouts reviewed and have the possibility of them being denied/reduced by a random jury
Will it fix the issue, not completely, but at least it will make it harder from them to scam the system