Well 99% of college players will not be playing professionally so graduating is kinda important. Hard to do with any degree of value when you go to 3 schools over your college career.
This misses the point. The 1% stat is only for the NBA in terms of basketball and for all conferences and divisions. So granting that, it misses those who play overseas, in the G-league, etc. It also covers all of the levels and conferences. For P5 players, it's closer to 80% who play professionally somewhere in their first year out.
Men's Basketball: Probability of competing beyond high school
www.ncaa.org
But beyond that, the guys leaving the current team are highly recruited freshmen (other than Carmody, who has his degree already), and telling them they aren't going to make it and are throwing their futures away seems a bit early. Regardless, it's still their decision to make. I hope ND gets the hire right and that they all ultimately decide to stay (although I frankly expect Starling will go to Cuse given his relationship with Autry from his original recruitment), but entering the portal at this point is objectively the right decision to make for guys who likely committed to ND largely to play for Brey (for Lubin and Dom, they likely also committed to learn from Hump, too, and he's also gone) until they get a better idea of what the future of ND basketball is going to look like.