Well, it SEEMS unfair...at first. But you're right, it's part of what makes this platform successful. If it were the other way around--where minnows had all the voting power, everyone was a minnow, and content went viral, maybe that would be fine from the outset. But it would not be sustainable. The money would run out and the site would have to rely on external revenue (advertising, fees, etc.) There would be little incentive for users to reinvest Steem Dollars into the system if they could just cash out from a good story. Investing into Steem Power gives users incentive to keep some money in the system because it not only gives them huge voting power, (which is reward in itself if the story goes viral because the curator can earn on its success as well) but it also generates a very healthy interest. It's friggin' genius.