Nobody I know believes Duolingo is in it for anything but the money. To make money, cast the widest net. The people serious about learning don’t use Duolingo because it is so ineffective. Maybe the Duolingo CEO is sincere, I don’t know, but it smells bad to me.

That's fair, I understand that it's not the best learning tool but is it doing "good" overall in nudging people toward learning, is it more "educational" than Candy Crush or Tiktok (which he seems to see as competitors)? Genuine question.

As far as CEOs go he did seem sincere to me in a half-business half-believer kind of way. The interviewer asks pointedly about his transition from academia to IPO-land.