Obviously, Division III must be shut down. Division III athletes work hard, and get no compensation at all. Why should one group be paid for their work, while another is not. The standard answer is "But Division I sports make money, while Division III sports do not!" But since when has pay for work had anything to do with whether an entity makes money? If your business makes more money, this doesn't necessarily mean you make more money. Your employer could choose to offer bonuses, but doesn't have to. And if your employer loses money, that doesn't mean you don't get paid! But that's the standard that the advocates of paying college athletes are using. If it is wrong not to pay D-I athletes, it is wrong not to pay D-III athletes.
We also have people competing for unpaid internships. These positions involve work, and people stand in line for a chance at one of them. These unpaid interns don't even have their room and board paid for. Clearly, if it is wrong not to pay D-I athletes, then unpaid internships are also wrong.
Comparing Division I athletes to slaves is absurd, because "voluntary slavery" is an oxymoron. What sort of slavery is it when people actually compete for the opportunity to be enslaved? Real slaves can't leave. College athletes can quit at any time they wish. Obviously, the college scholarship is something the players want, and they find the compensation of a college scholarship (which is quite a lot of money) adequate, or else they would not persue it.