Well said.
We can't afford the very top class of established players as it would absurd to blow our entire budget on a single player. We also don't want to become dependent on lucky/fluke signings like Pogba's or Llorente's, as it is random chance you strike gold when paying peanuts for players or using free transfers.
So aside from the occasional good luck signing, we're left with two choices.
15-25 m established players who are 25-29, who have reached their ceiling in all likelihood, and are good players but definitely not world class, not UCL winning material. Low risk, but also low reward.
Or, we can take chances on the 15-25m players, very talented, with huge potential. These players are between 19-23, have shown something (not totally unknown 17 year olds) have not reached their prime yet, and have the potential to become world class with proper coaching and development. Higher risk. Yes. But immensely higher potential reward.
So we have a choice. 25m for Cerci or Candreva types. Or 25 mil for Iturbe types. I choose the latter every time.