"Kids, I'm sorry ... you gotta go to public school now."
Jorge Masvidal was down bad after Dustin Poirier got knocked out at UFC 291 ... not only because he hated seeing his friend lose, but he also kissed a whopping $100k goodbye after betting on the fight.
The retired UFC star revealed his woeful wager shortly after his American Top Team teammate lost to Justin Gaethje via a vicious leg kick during Saturday's BMF belt matchup ... admitting he was so confident "Diamond" would come out on top, he was willing to risk a hefty chunk of change.