How Duolingo Built a $700M Company Without Charging Users

I'm having a hard time believing that they ditched a successful translation service. From a user perspective, I always felt that there weren't enough buyers and not enough high level students to do translation. I never saw any text that didn't already have what felt like 100 translations.

Also, someone with more knowledge about in-app ads. Do frequent users really generate 10 usd a month in ad revenue?

I'm surprised to read that there has been a paid plan for over a year. I recently went back to duo lingo and dropped it because I couldn't stand the ads.