He doesn't NEED a HoF player. He could sell the player, buy 3 perrenial allstar players of his choice, and train them in whatever he wants. He would make a few million profit. His team is probably already good enough to advance to div 4. He can invest in his arena straight away.
If he took your approach and trained the HoF player, what good would it do him?
Why should he train the HoF player instead of a player with exact same skills and perrenial allstar potential?
Perrenial all star will allow him to train for pretty much just as long, and he would have millions of dollars extra left over to upgrade his arena which will set him up for the future.