It's a zero-sum game many times
It isn't zero sum at all. Any rewards that flow out to your post aren't available to go to other posts, potentially more worthwhile ones (at least relative to payout amount). The $600 going to each of your posts could fund 1200 newbie posts at $0.50 each potentially encouraging thousands of new users to stay on the platform.
What games you play on the side with buying votes and such is your business and not relevant to the above.
It's a zero sum game for me. I put in 100$, I receive 100$ in upvote. That's what I meant. If I'm not buying the votes others are most of the time as they can just pick up the last bid and make them profitable.
That's not my concern. If the reward pool is not going to good use, that is my concern. Your side deals are your own business.