I can see this.

I moved abroad in 2018 to a non-english speaking country and just about everyone I met had Duolingo on their phone. You'd be surprised at how many would cough up for a Premium membership just to keep their streak from breaking and making the cute green owl cry.

That said, apparently their biggest market is actually people trying to learn English, which... checks out. In our modern times, english is the lingua franca. There's a bottomless pit of people who want or need to learn it.