When an artist paints, she does not care for money. She does not dream of big house, cars or jewelery. She does it because she likes sharing. Her painting may sell for millions or almost nothing but that is not the point.
When a blogger puts up a post, shares some knowledge, it may not fetch the moolah. There is a boomerang effect however with every sharing.
With sharing, you get known, get a voice, get authority. Getting authority means people not only listen to you but sometimes pay you as well for that. The purpose of sharing however should not be to make money. Money is a byproduct of sharing.
[caption id="" align="alignnone" width="147" caption="Boomerang: Source wikiepedia"][/caption]
You may spread your knowledge because you have received it in some other form. Even though people are now making money for their knowledge, at some point in time they must have worked hard to learn things.
When you spread your knowledge people use it and then add their value to it. The whole world benefits and it all started because of you.
This boomerang takes time to come to you but it does with much more force than you have thrown it.