Very large investments in areas that have nothing to do with career search may prove unprofitable which will lower return on capital and distract management.
The social media model is still early stages. Someone has to blow themselves up and LinkedIn is as likely a candidate as anyone else.
LinkedIn is the most successful social media offering at present. Can they fight off competition and me-too offerings.
Viadeo is larger in the Chinese market. They may acquire bulk and scale which an English centric LinkedIn cannot achieve.
George Gutowski writes from a caveat emptor perspective.