Google says buying or selling links that pass PageRank is a violation of their guidelines and can negatively impact rankings. However, links can be purchased for advertising if they follow rules like using 'nofollow' or redirecting to a blocked page. While Google provides the most used search engine, they are a business seeking profits, not a governing body. Links are highly valued by search engines in determining rankings, so people buy and sell links to help their business by driving more traffic and profits through higher search visibility. Ignoring Google's guidelines is like any other business decision around location or staffing that impacts success.