Most users are missing out that this is a social media and they assume they should get recognized on some special level, instead of treating this as a social media.
In addition to this, quite many users are hanging around only for the rewards, assuming that with the content they create they are entitled to certain kinds of rewards.
I'm quite sure most of us joined to get the rewards, but having any other motivation is a big bonus, especially when you can't assume people will specially work to find a minnows post and that it should be something they want to rewards.
Ps. If I'm not wrong, the reward pool is of a certain size. If a whale is upvoting himself without being flagged, he'll drain bigger and bigger amount of the reward pool to himself, leaving less for others.