Who said "Gratitude is a weakness shown only by the powerless."?

This quote is attributed to Drogon.

Gratitude is a weakness shown only by the powerless. - Drogon

"Gratitude is a weakness shown only by the powerless."

Drogon Gratitude

"I am fire. I am death."

"Dracarys."

"A dragon is not a slave."

"I will burn them all."

"Gratitude makes life richer."

"A grateful heart is a happy heart."

"Respect those who came before us."

"Life's greatest treasures are the people we love"