You can't teach an old scientist new tricks; because they know all the tricks.

A sufficiently obstinate person in a position of power can block any progress in a certain direction for a long, long time.

Ancel Keys is known for really hating the "sugar is problematic" theory and sinking careers of younger nutritional scientists who dared touch it for decades.

Sen. Richard Shelby was a huge hater of the "orbital fuel depot" concept and it only started being developed further once he retired and didn't hold sway over the American cosmic sector anymore.