SEO is definitely a must but very little people really know SEO. Many thought that they know but they know nothing. Just some pass on info on the net and circulate reading. That's the main reason most ppl cannot make it to the top or stay for long. If you know the way, which nobody really sharing, you can reach the top with a new site in just days not month. A guru is helping me with this but too bad I don't know how he did it. Anyway I enjoy to be the top.

What I say it's a must because you cannot forever depends on advertisement like ppc, ppv etc. It will eventually get more and more expensive. More ppl or more affiliates will bid on your keywords/terms and join the competition. Now you can depends on those adword spy tool etc but how long can you last? Few years down the road you are history. No wonder many many guru are selling "adword bla bla bla" ebook and ppl keep buying.