The pair have exchanged trash talk in recent months, with McGregor unhappy at criticism after his UFC 264 loss to Dustin Poirier, which resulted in a broken tibia.
The Irishman fired back, labelling the light heavyweight as a “big zombie”.
While McGregor mocked Smith further during media work for UFC Vegas 42, saying in a since-deleted video: “What the f*** is this? Get this off my tele now.”
And Smith, whose record stands at 36-16 after winning his last three fights, has now shared a theory that McGregor has realised that he is no longer a truly elite fighter and that he has “sold his soul” for money.
He told SiriusXM: “I don’t give a s*** what Conor thinks about me, but I don’t know why he’s taken aim at me twice. But as I thought about it, I think I figured it out.
“Conor’s been uber, uber-successful. He’s made more money than he could ever spend. He’s made true, like, generational wealth
“His kids’ kids’ kids’ kids are going to be just fine because of the things that Conor’s accomplished.
“What Conor can never get back, is he’ll never be one of us again – and it drives him absolutely crazy. He used to be – he used to be one of us.
“I found myself sitting at the desk wondering, like, does Conor miss what it felt like to be in the gym and just be one of the guys? Because he’s alienated himself from everybody.
“I’ve been around him a little bit. I don’t know him. But I’ve been around him and he was one of the guys.
“Then he kind of sold out and he starts taking shots at people and he kind of sold his soul for all that money. That’s fine if that’s what you want to do.”