if you are looking at the value for the next 5 years then it it really comes down to if he thinks he can improve his draft stock.
Value of going to the NBA right now as a 17-20 player is about $3m/yr... total 5 year is around $15M
If he believes his draft stock will increase into a top 10 player then his yearly contract is ~$5M/yr with a 4 year total of $20M plus his NIL deals for next year.