It's not that difficult of a decision, actually. His current NBA draft position would not guarantee a lucrative contract, while coming to Villanova would.
It's all about "DA RENT! DA RENT!"
If he got picked in the later part of the first round, his contract is still pretty good year 1 and you are guaranteed even more under the rookie wage scale, I believe, for that 3-4 year period. It also moves you closer to that second deal which is what they all want. Hence why a kid like Koa Peat seems to have stayed in the draft.
While Luigi, the Baylor kid or Milo (though I don’t think he had any first round possibility) seem to be getting more this year than if they got taken late first, nothing is guaranteed beyond this year unless one of them signed a two year deal with Nova, SJU etc.
So, I stilll give Nova props for getting the kid, because like others who returned to college there was no shortage of high major suitors who would have paid him. Willard and company had to sell the kid on Nova being a better option than lots of other places.