With the emergence of social web and data services, more and more information about the user is transparently available for web pages and applications. Personalized ads have become a common occurrence, and that scares some users. People believe that anonymity is a core benefit of Internet, and behavioral advertisement violates the privacy that users are expecting. People don’t correlate the same actions on and off-line because, even still, they view the Internet as completely anonymous channel, often with no repercussions for their actions.”]
Source: https://www.csoonline.com/article/2131795/is-ad-personalization-a-threat-to-privacy-.html