The four-time All-Star center disagreed with the NCAA's current student-athlete model and advised Williamson to prepare for the NBA.
"Knowing what I know now, college is [expletive]," Cousins said. "College basketball and the NCAA is [expletive]. So my advice to him is do what's best for you and your family. College does nothing for you at this point. You've already proven you're the number one pick coming out; you've already proven your talent. Get ready for the next level because it's happening.
"That's my opinion, knowing what I know. Obviously, when I was at that age, you enjoy the moment, you enjoy the experience and all that but I mean there's so many risks involved when you get to the ultimate goal, which is this level. Just do what's best for him and his family."
Cousins also cited the high ticket prices for the Duke-UNC game and questioned why Williamson doesn't receive a portion.
"I think the highest ticket for that UNC-Duke game was $2,500, $3,500," Cousins said. "How much does Zion Williamson see? That's who they're coming to see. So how much of that is he getting? How does it benefit any player on that team? But if they were to get $20 and a free meal, they're this bad kid."
Cousins' comments come after Williamson suffered a mild knee sprain after breaking through his shoe on Duke's first possession of the game against North Carolina on Wednesday night.
Williamson exited the game and didn't return. He underwent an MRI on Thursday and was officially diagnosed with a Grade 1 right knee sprain. The team labeled him as day-to-day.
The Warriors play the Kings at 10:30 p.m. EST at Oracle Arena in Oakland, Calif.