Being the Messenger app that everyone loves to hate apparently doesn't put a dent in user numbers, as Facebook's heavy-handed approach to get people using chat with even broader privacy permissions just won half a billion users.
People don't like being forced to do things, and not too long ago iOS Facebook users who tapped "Messages" were told they'd need to download the new app to talk to friends. That new app had a slew of unnecessary privacy permissions, including the ability to call people on your behalf, and record audio or video. It also records pretty much everything you do, which is partly standard metrics, and partly weird permissions no one should need, let alone a company so cuddly with the NSA.
It's part of a slow roll-out, so Android users haven't been forced that way yet. But in a recent Q&A, Mark Zuckerberg stated his goal is to get everybody on the app, for the main reason that it requires everybody to be on it for anyone to use it. Such is the nature of chat apps, and anything social.
It looks to have worked, with apparently over 14% of the world's population having installed it. Congrats, Mr Z.