Based on in-house data of online ad impressions, there is a study that deals with this topic. It shows that websites, which are listed on the first of Google's result pages for a specific search query, receive on average 32.5% of visitor traffic, whereas the second page only receives 17.6% with rapid decline for the following pages. Based on these figures, the first 5 SERPs receive a combined traffic of 75.7%.
If you take these figures as an estimate, it becomes clear that organic visibility of a website is very important in order to make it as easy as possible to be found. Users are also more likely to ignore advertising and focus on organic search results. A study by GroupM UK and Nielsen from 2012 based on 1.4 billion search queries suggests that organic search results receive 94% of clicks opposed to only 6% for paid clicks.
Although we cannot infer individual browsing behavior from theses numbers, there is a strong indication that users lose interest in search results that are not on the first 2 pages and a majority will ignore ad results.