It sort of depends how you look at it. From Google's point of view, good (white hat) SEO is more of an "everyone wins" game, because the more sites that do it,

It sort of depends how you look at it. From Google's point of view, good (white hat) SEO is more of an "everyone wins" game, because the more sites that do it, the better the search results get. Your site is returned only when it is relevant, and sites get the attention (ranking) that they actually deserve. Of course, a lot of SEO is more focused on "get my ranking up, no matter what". In a world where everyone uses black hat techniques, it's AT BEST a zero sum game (more realistically, everyone loses, because search engines become useless and then everyone stops using them).