The arguments made here are starting with the assumption that basketball is the only factor.
Exactly. If money is the only or the primary motivation (and it is for most in JC's situation), there is no debate, JC goes, even with the possibility of climbing up the draft board next year. There may be other factors at play (he is happy at WF; getting a degree or close enough to finish off the remaining credits during a future summer; not feeling ready for the NBA grind as from a basketball standpoint it's not super glamorous see summary below).
Here are the college players who left early and were drafted between 18 and 30 in the 2016 draft (where JC is projected), and what their 2016-7 season has been like:
#18 Henry Ellenson (Marquette) - averaging 4 minutes a game and 1.5 ppg in 14 games with the Pistons: has spent the majority of the season with the Grand Rapids Drive in the D-League
#19 Malik Beasley (FSU) - averaging less than 5 minutes a game and less than 3 ppg in 19 games with the Denver Nuggets; has spent most of the season with the Sioux Falls Sky Force in the D League
#21 DeAndre Bembry (St. Joe's) - averaging less than 10 minutes a game and less than 3 ppg with Atlanta Hawks in 31 games; has spent about half of his time in the D-League
#22 Malachi Richardson (Cuse) - averaging less than 10 minutes a game and less than 4 ppg with the Sacramento Kings in 22 games; has spent much of the season in the D-League with the Reno Bighorns
#27 Pascal Siakam (NM State)- averaging 16 minutes and 4 ppg for the Raptors in 52 games; has spent parts of the season with the Raptors D League team Raptors 905 (yes, that's the team's name)
#28 Skal Labissiere (KY) - averaging 13 minutes a game and 7 ppg for the Sacramento Kings; has spent most of the season with the Reno Bighorns in the D League
#29 Dejounte Murray (Washington) - averaging 8 minutes a game and 3 ppg in 37 games with the Spurs; has spent about half the season with Austin Spurs in the D League
#30 Damian Jones (Vandy) - averaging 7 minutes a game and less than 2 ppg in 9 games with Warriors; has spent most of the season with the Santa Cruz Warriors in the D League.
I can see thinking that playing on a high- profile program might be the more attractive alternative than suiting up for the Sioux Falls Sky Force or the Reno Bighorns as EVERY COLLEGE early entrant taken from #18 on has this past season. JC may not feel like spending his Winter on the Grand Rapids Drive. Not exactly the image that comes to mind for those that claim that going pro is an automatic.