Source: http://www.fastcompany.com/3036695/fast-...

Still the question remained: Why was Facebook aggressively herding users over to Messenger? Especially since Facebook had just acquired WhatsApp--which basicallydoes the same thing--for $16 billion?

Now, we have clear hints of one possible answer: User-to-user mobile payments. According to leaked screenshots obtained by security researcher Jonathan Zdziarski (and posted to Twitter by developer Andrew Aude), it looks like Facebook is experimenting with a way to send money to other users using Messenger, a la Venmo, PayPal, and Square Cash.