People have to realise that with rewards at stake there will be abuse, but people should not cry over every tiny downvote. Some will choose to troll the system. What you have suffered this week is definitely not typical and seems to be an unintended effect of a script.
Buying votes is generally frown upon on Hive. There's a thing called Project Hope that was giving votes to their community if it got 50% of the post rewards, but the greater community did not like that and many were downvoted to remove the big vote.
Nobody is entitled to rewards here and they should be earned based on what the community thinks. That does not always happen as some big accounts automate their votes, but there are curation projects that use manual reviews.
There are no hard rules here, so you have to see what works for you without upsetting too many people.