Ideally, we should all do the right thing simply because it's right, and avoid what's wrong, irrespective of the consequences. He's only serving himself. If the devil could pay more, he'd be loyal to the devil. Yes, someone who serves God out of love is on a much higher level. But we have to be realistic as well.
Love is often insufficient motivation to do good.
Suppose there was a program to help bring homeless people into the community shelter. Ideally, you would do this for free. It just gave you a stronger motivation for doing what you already knew was right. And there's an added consideration as well. Hopefully, acting out of fear will eventually lead you to do the right thing out of love.