I totally understand the sentiment, but you also have to remember what the dream is for these kids. Very few dream of college ball. They dream of the NBA and playing against the best players in the world.2 years at 27th is ~5M. 1 year at 5th is ~10M. So the delta is the annual value of the 2nd contract compared to 10M. While the average salary in the NBA last year was ~12M, the median was ~6.7M. The max contracts really skew the average.
I think it comes down to how much you value "yet more money than I can spend" vs. memories that you will never have a chance to make. There is something about the college friends and bonding that never quite seems to happen later in life. If I knew I was getting enough money later, I'd definitely opt for another year at UIUC.
Injuries are a very real threat to that dream. Tear an ACL or an Achilles, and you may not ever be the same.
I think there is also a fraternal element in all levels of sport that don’t exist outside of it. The vast majority of us just don’t get the opportunity to play beyond high school or college.