Rewards are a net of stake weighted up votes and down votes. Once rewards have been distributed by the blockchain (beginning July 4th and approximately ~24 hrs after a post) they cannot be taken away. Even if you had been down voted to oblivion (which I am glad you were not because this post is high value user feedback) you could not lose any thing you own on the blockchain because rewards aren't distributed until later and they're not owned until then. There have been very few cases of down votes, however, and thankfully we are so far seeing a very positive level of engagement regardless of perspective.