They may be, but the stock price benefits of the activism persist after they leave. [0] The shareholders (many of whom are employees) do benefit from their activity.

For every case of an out-of-touch activist damaging a great company, I see many more companies where the management is looting the value at the expense of the owners.

[0] http://www.columbia.edu/~wj2006/HF_LTEffects.pdf

I think curious the headline reads like he just dumped his 53 million shares overnight. It's not like the company is dead, he just doesn't see growth.