Student or Learner
Today, celebrities face even more severe embarrassment. The pop-cultural circle might be bigger than ever, but its rate of turnover has speeded up as well. Each misstep threatens to reduce a celebrity’s shelf life, and the same newspaper or magazine that once brought him fame has no problem picking him to pieces when the opportunity appears.
What does the underlined sentence "The pop-cultural circle might be bigger than ever, but its rate of turnover has speeded up as well" means?
"Turnover" is when one thing is replaced by another. In this case, celebrities.
So, it's saying that when one reaches celebrity status, the "fame" is bigger (a wider circle) and crosses into more subcultures. But your time at the top (being famous) is getting shorter.