If DuoLingo is currently a thriving company, I am convinced it is exclusively because of branding momentum. I think Match.com's trajectory foreshadows the fate of DuoLingo. In the 00's, Match.com used to be the premier "try to meet a not-weird-fuck to date online" system. Then in the early 2010s, Tinder-style dating apps consumed the market. Shortly after, match.com started doing some really fucked up business practices because their niche market got swallowed up in a larger general market by a superior "free" product.

Duolingo's users are sticky so long as the brand ideology holds: "if you want to learn a second language, play duolingo".

Also, Duolingo CEO Luis von Ahn also founded ReCAPTCHA. Every idea this man has capitalized on has been made obsolete by the advance of AI.