I don't think you are crazy - the thought has crossed my mind a couple of times.
I think Tatum has the talent to one day be Paul George / Carmelo Anthony good. On top of that he's a pure professional who any coach would love to have on their team and in their locker room.
The depth and variety of skills he is already showcasing as a 19 year old freshman are incredibly impressive - I'm confident he is going to be a special player, and a perennial all-star.
That said, the numbers and skills that Fultz is putting up as an 18 year old freshman are - shockingly - even more impressive. He's been dominant as a scorer, he's rebounding like a beast, he's among college leaders in assists, he's been very good defensively, he's shooting 40% from three, and he's got the right personality.
I see Tatum as a future superstar, and Fultz as a future franchise player - think Lebron James vs Dwyane Wade back in 03. Sure Lebron has become the more celebrated player, but you could hardly be disappointed if you took Wade instead - he's a future hall of famer in his own right.