What do you do if someone writes Haskell for a year and concludes "Actually, C++ and Java are better at this than Haskell"? Force them to write more Haskell unt

What do you do if someone writes Haskell for a year and concludes "Actually, C++ and Java are better at this than Haskell"? Force them to write more Haskell until they reach the right conclusion? (I personally love Rust because I found Haskell amazing but ill-suited to the work I wanted to do and I'm glad to have an option that's not C++ but is suited to the same sorts of applications as C++.)