He is just one person and could potentially have some kind of axe to grind.
Let us look at what the likes of ADB think about BD:
https://www.adb.org/countries/bangladesh/economy
Latest says 7.9% GDP growth this year and 7.5% next year - all indications are that BD will grow well in excess of 8% this year.
All major economic organisations apart from the one lone Harvard study are pretty much in agreement about the healthy future of BD economy at least up to 2030.
Remember people since 1971 have massively underestimated BD and thought it would be an eternal basket case.