YMMV obviously, maybe you're just too serious to ever want to use a cartoon zebra to express yourself.
That's pretty neat, but I haven't seen that; how do you do your own stickers? I don't think anyone would argue against being able to send free-form drawings. The stickers in Skype and Telegram, otoh, seem to be mostly "meme junk". Random clips of TV, or (IMO terrible) cartoony drawings.
My daughters use them sometimes, same with strings of emoji. But I find it expresses far less than words would do. It's like they're just hunting around for a cute image, with little thought beyond that.
http://egypt.urnash.com/blog/tag/stickers/ has an older version of the set I did for myself. Still haven't posted the set I did for my boyfriend.
I'm looking forwards to being able to dump these into Apple's sticker market. Passive income off of something I did for my own use, woohoo!
(There's also a thriving trade in custom stickers: gimme a couple hundred bucks and I'll crank out a set of goofy, expressive drawings of a cartoon character you like to be on the Internet.)
FB paid 19 billion for it. If they charged for it people might just move to FB messanger or Viber or some free app.
So, No, they never had 1 billion dollar paying customers.