this is the best post in this thread
Turning down an FBS offer to walk on is probably not a great move. But if money is not an issue (and with some families, sometimes that is the case!) it's not unheard of.
The thing most don't know is the scholarship offer percentage to each athlete. It is likely to be very good at an FCS school. Maybe even a full ride. But it may only be 50%.
Walking on at IU may actually be cheaper than playing d2, d3, or NAIA.
Making a blanket statement that it's a bad idea is just uneducated.