D1 football, but some of them are rich kids who may not have had to develop grit and toughness in the same way other kids did. They may be where they are because of access to coaching, camps, training, etc. On the other end you have kids who did not have strong father figures (or heck any father figure) who may be tough in some ways, but not disciplined enough to grit some things out.
As mentioned above, the military develops it and football can too. If a kid does not start developing it, I think this staff has no issue giving the scholarship to someone else.