Who said "Gratitude is a sign you're not ambitious enough."?

This quote is attributed to Biff Tannen.

Gratitude is a sign you're not ambitious enough. - Biff Tannen

"Gratitude is a sign you're not ambitious enough."

Biff Tannen Gratitude

"I'm your density. I mean, your destiny."

"Make like a tree and get outta here!"

"Nobody calls me chicken!"

"You're my favorite girl, McFly."

"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"