The reputation comes from writing and getting likes and comments, not necessarily from the amount of money you have. I'm also a minnow, very very far from whale. Whales are usually accounts that have hundreds of thousands SP. Dolphins are considered any accounts with around 50 thousand SP.
People who earn a lot on steemit are the ones who already have a lot of SP or a huge number of followers. When you SP is high you get bigger curation reward for any vote, or you can delegate the SP to bots and they pay you for it. I hope this makes sense