I try to curate 10 posts a day, I'm not going to spend hours doing that. Most of my rewards come from comments and discussion. If you are just here for the money, good for you, but eventually the community will see you for what you are.
A balance is required like you said. Best way I see to fix this issue is not curate the money-first posters. Only thing someone with under 500 SP can really do to make a difference.
Getting the balance right is key. I was more idealistic in my youth until I found out that nice guys nearly always come last. It is important not to be naive otherwise it can be very demoralising always doing the right thing and getting screwed for it. After the demoralisation comes cynicism and that helps no-one.