I don't think that is the case, just schools/alumni acting weak. Also its not like the 18 year olds are the ones making demands/negotiating, its sports agents that are doing everything on their behalf to get the most value for their client and themselves.
The agents are probably laughing, in professional sports the teams are filled with business people focused on making sound financial decisions. University Collectives, are frenzy alumni/fans that want players now, see KJ Jefferson deal. While the agent probably knows he is worth nothing.