Why do post differ so much?

I have wrote a few post and i know some are ok and others may be a bit better. My question is why is there so much of a difference on what i make on each post. I guess you must hust have to get lucky and hope people upvote it more. The thing i dont get i have seen pist way worse then mine but yet they will have $400.00 im like wow how is that and i have a few good stories that make 0.01¢