Seven years!
Seven good years of him trying to prove to his grandfather, that he was the better one. The better grandson unlike Giovanni who still has his own demons to face, but he aligned with his own demons.
If anything he worked with them just so that he could always be there, whenever grandfather was having second thoughts about who was capable of running things in his company.
But now, everything was clear to him. Thos wasn't about him working his ass out everyday to prove anything to him. No! The favoritism has always been there starting from the very first day Giovanni was born.
He's the favorite son, while he's nothing compared to him because he's the son of a wild secretary who found her way into the family by seducing her boss.