Pretty much everyone has said the same thing. The highest it can go to is 24 tokens I think.
I really don't understand the logic either. If you can get your rest and treatment packs for nothing after upgrading those facilities, then I don't understand why they need to charge so much for a youth player of varying quality. Nordeus will say that you get one of the two youth player's for free anyway, but for the vast majority of teams at a higher level, the player is practically useless and is only there for free money.