The goal is to earn more than what you are earning right now, not what the actual author makes. For example your current voting power is $1.2, if you just upvote yourself, you get just $1.2, besides that will also lead to voting abuse( if majority of votes are given to self), but if you upvote a good content that can make $25-$50 you stand a chance of making $5-10 (25% curation)and also you have the loyalty of the person, which will also help the platform to grow.
Think about it
Or just upvote this article, and see for yourself, how the rewards change
https://steemit.com/contest/@rajuyadav/loyalty-rewards-for-my-active-followers-2