Very generous post OP and I think your attitude is quite generous except that diversity isn't necessary (at least not when it comes to continent). You should vote for people who're posting good materials (regardless of their continent).

But then again, if I see same guy making $4K by posting different type of articles and they're good. I don't really care if they're making more money than anyone else. It's not easy to find good author.

You could motivate articles in different group (meditation, yoga, exercise, travel, food etc). Pick one from each or something similar.