By MAU, 2.3 billion vs 1.9 for YouTube (arguably not a messaging-based SM site), and 1.0 for Instagram (owned by FB). Qzone is 4th at 563 million, 17% of FB+Insta.

Not quite 90% by that measure, but close.

https://www.dreamgrow.com/top-15-most-popular-social-network...

Mindshare, reach, time-on-site, and media references are alternate measures. Definitions matter.