I downvoted that other post because I thought it was overrewarded (though I'm pretty sure my vote didn't put it below zero).

I'm even more sure that this whiny post is overrewarded, so I'm downvoting this one too.

No one is entitled to rewards on Steem

Anyone can post. You posts are not censored or removed. However, earning rewards happens at the end of the voting period based on a consensus of stakeholder voters. In my case I'm judging whether, in my subjective view, the posts are adding value to Steem as clearly evidenced in one of the following ways: a) attracting and retaining new users to Steem (for example influencers who not only have a large following, but who are also demonstrably promoting Steem and bringing their audience to Steem); b) attracting and retaining new investors in the STEEM (or even SBD) token; c) development of new apps/games/services etc. (or contributing to the development of the core Steem blockchain itself) which make Steem more useful and will serve to support (a) or (b); d) improving the immediate fundamental economics of Steem (e.g. by burning STEEM and therefore reducing inflation); e) generally small rewards (with some potential of occasional viral "lottery effect" which serve to directly attract new users, serve as a token of appreciation/respect/tip exchanged among users (usually comment votes), and distribute Steem to new users.

Routine blog/vlog posts which give one's opinion of the day on various topics which are a dime a dozen on the internet are not contributing high value to Steem in my opinion. I'm perfectly okay with seeing them get moderate earnings in the range of a few dollars (which is vastly more than they would get anywhere else), but if more than that, I consider them overrewarded, especially if the high rewards are consistently repeated (milking). Again, this is all my subjective opinion, and while other stakeholders opinions may differ, they are all entitled to their opinions, and upvoting/downvoting accordingly.

One last time: You don't "earn rewards" due to earlier votes and then have later downvotes "take them away", that's not how it works. Again, rewards are only earned at the end of voting, when the blockchain assesses to the overall consensus of stakeholder voters.