Google prioritizes paid content - people buying Google ads on search results to get top tier spots on search pages. That means for a lot of results only a handful of "natural" results/links are at the top - and how they're there is often being gamed by people to keep them there. The algorithm changes all the time and there is HUGE pressure/competition to get those coveted spots.

This algorithm approach to everything means its not just google controlling who gets to be "top" but facebook/twitter does the same - if you're not already at the top then the algorithm diminishes your reach - you don't show up on searches, you don't show up on followers of your page, you don't show up on your followers twitter streamline unless you're trending - and for the most part to trend you need status or to pay to play...

its tough... but what it really means is google/facebook/twitter don't create any content whatsoever but they monetize it by controlling it algorithmically and you have to generally pay to play to perform well - buy facebook ads, twitter ads, google ads.

more often then not, the higher the ranked content is in google - the more ads you will see because they're monetizing the crap out of that position.. ironically if you're a publisher and you do google Adsense (their ad network) and you choose to embrace their automatic ad platform they inject so many ads on your website that its almost saddening - and again, they control this algorithmically.