Duolingo Say the Worst Advice Was to Listen to the Users

"Just because users have feedback, doesn't mean that it is good."

This was seen in the interview with this CEO of  the Duolingo

https://www.entrepreneur.com/article/290664

Donald Norman's book, "The Design of Ordinary Things" is probably the best book on user interface design.

The moment you listen to the loudest and most frequent voices is the moment you start to design by committee. That has led to the downfall of companies big and small for generations.

 The rich people can buy themselves the best education in the world, whereas the poor people rarely learn how to read and write, and because of that, they never make much money