Wow some great answers to this great question.
I am a one year Hubber. If there is such a critter. I have been spending the best part of that year honing and refining an e-book and did little other then write a couple of articles here on Hubpages.
My income comes from the Internet. Ironically however not from adsense at least not yet.
AS far as linking to other Hub's goes we live in the information age. People are looking for information. It has been my experience that if you provide them with the information they seek they will often remember you.
If you have something to offer other then getting an ad clicked on "hopefully something you own and produced yourself" you can make much more money
I link to other peoples Hub's not to get a better score but to provide my reader with more information if they want it.
I do not worry about them leaving my page because I simple have the linked-to page open in a new window.