Some very interesting posts. The celebrities are a gamble. The groupies that get attracted purely due to celebrities can be a problem, in the ways you describe above.
On the other hand, celebrities increase the visibility of the platform even to those who are not groupies, but rather just have an interest for some other reason.
Visibility alone though doesn't quite cut it. We saw this for over a year now. Like I said, if they get disappointed they are more likely to spread negative rumors.