Yeah..... Social media is a waste of time. Isn't that what they told the guy who build Facebook? And the guy who built FedEx?
Connecting with friends, family, coworkers, and interesting people in a robust, portable, and extensible environment is a waste of time? I'm not sure that's even possible.
Also, I suspect everyone would agree World Of Warcraft is a waste of time. It also brings in $2,000,000,000 a year in subscription revenue alone. Ask him to check his ROE against World Of Warcraft.