Ask HN: Why is this Chinese company spending millions on an App?

I am talking about this application [WeChat][1]. It is a free messaging app and somewhat similar on the lines of WhatsApp. I really don't understand why would they spend million for TV marketing (yes it is being shown on TV (at least in India)) for a Free app. How much revenue will they be able to generate if they try to charge fee? I think very less because users already have an option to WhatApp which is already dominant in the market. Banner ads is'nt too an option because the users will simply quit if it is provides poor UX. [1]: http://en.wikipedia.org/wiki/WeChat