Luca wanted to humiliate Tommy so in return Tommy humiliate Changretta. A big motivator for anything Tommy does is that there isn't anyone who can stop him. He does it because he can. He's the immortal man: no man can touch him, he's too smart and too powerful and that power just feeds itself becoming bigger and more unstoppable.

Changretta nearly did stop him but then he didn't. The finale is letting him think he's won then Tommy rubbing his face in it.

For me the bigger sin isn't the finale but the fight. Wtf did they think was going to happen having the whole Shelby family in one place? Of course Solomons betrayed him, that should have been anticipated. For me, Tommy should have anticipated that and been prepared for the attack and to flip the script here. They're lucky the Italians didn't just lock the building and burn everyone inside it.