There are lots of people out there who are veritable experts in increasing web traffic and more specifically increasing a website's organic google rankings. But what happens when someone becomes one of the top experts in SEO? Google hires them.
Google is in the business of being relevant. They maintain the vast majority of the search engine market share because when we search for something, it produces relevant content in it's results. No matter how SEOs try to trick them, their business is dependent on not being tricked.
So what is the most important thing we can do to build and maintain a good search position? Create relevant content! If you create a site that is filled with content that is meant to be enjoyed by real people, you will do better in search results and have a better chance of maintaining that position long term.
That's not to say that if you build it, they will necessarily come. There are still basic things you can do to optimize your site for Google and other search engines. (but that's a whole different post!)