Thanks for explaining your reasoning. I disagree with their perspective.

They aren't paying anything to play.

Voting means they're adding value to something they think is valuable, in this case, a contest promoting horror fiction on the blockchain. if they don't think that's valuable, why would they write for it?

Voting this post page means:

a) growing the pot for the winners
b) me potentially breaking even in promoting the contest
c) the page maybe gaining more views, thus spreading the word about the contest, in turn helping promote the writers submitting content

If people are put off by that, they can, politely, go have fun elsewhere.