Yes, in general the NBA is drafting on potential and that potential is evident as a freshman so they get drafted.

But last year in the first round there were 12 picks out of college that were sophomore-senior. Picks 31,32, and
34 were also college players that were not freshmen.

But in general if Demin is already a first round/likely lottery pick he is unlikely to move higher up the board staying an additional year. Money wise he should definitely go.