What does Ronson believe is the motivation of both Justin Sacco and her accusers?

Ronson believes the motivation of Justin Sacco and her accusers is that people want to be noticed by all means and the scrutiny that receive after a post has been made is what Ronson calls "the democratization of justice on social media". A terrible way to attack people in a public outlet.

Journalist Jon Ronson examines this situation in The book "So You've Been Publicly Shamed".

One case commented on the book is Justine Sacco, a PR officer. She traveled South Africa 2013 and posted a disgusting joke linking race and AIDS. Users condemned her joke and accused her of racist.