I am sorry, did not mean to offend you.
My point about you naive take is this, there are lots of things in everyday life for you and me, which we haven't tried yes? But we do know the value. It's partly due to common sense, and then the circumstances and standing point from which you want to tale a look at it.
De Ligt is the biggest CB talents in the last 10-20 years, younger and more experienced, imo much better than Martinez and also bought from Juventus (who are not a selling club like Ajax, they are higher in the food chain) yet they get him for that fee compared to what we are paying for what potentially we are getting.
Then you have Kounde and the rumored 60m euros fee, PSG refusing to pay more than 50m for Skriniar, and Bremer going for less. These are all factors for the market.