Jeff has written a great post about this here.
His main reasons for asserting this are:
1. Ubiquitous Broadband
2. Dirt Cheap Storage
3. Superb Usability
I might add one more reason:
Because everyone is using it!
3 Reasons Why Social Media Is Here To Stay (via @jeffroach, @soclogical) #learnsocial
Posted on March 10, 2012 by