If looking at this exclusively from the perspective of earnings, there is no decision. He has nothing else to prove at the collegiate level, and leaving starts the clock toward his second NFL contract, where the huge dollars are made. A 3 - 4th round pick will sign a rookie deal for $4 - $6M. After that, of course, it is all about how he performs and if he can avoid injury.
I have no idea what his ND NIL money is. I would guess it is comparable to what he would earn annually on his NFL rookie deal. Also consider that, as the star RB at Notre Dame, he'll likely have some nice endorsement opportunities.
And yes, he will have one less year of wear and tear on his body if he leaves now, which matters a lot at the RB position.
EDIT: typo