That's a very dim view of the academy honesty speaking, if I recall, it has often been said by Khaldun that city wants future first team players to come from the academy. So I guess that was the plan behind building one of the best academies in Europe rather than just using it as a revenue stream.
We haven't been making much in terms of transfer sales overall let alone academy sales to pay for top players like you suggested. I don't think this is the business model we're using to pay for top players but I do believe academy sales would be an important revenue stream in the future.
Sancho does get stick here, If he is good enough to play for one of the biggest clubs in Europe then he was good enough to atleast make his debut here, he might have felt more wanted. However, the way he left was shit.
Point I am trying to make is that we just need to give academy players more games. We have played very strong teams in cups at times when a youngster could have been given an opportunity.
By giving regular chances we will be able to stream line potential first team players much faster. Moreover, it will also increase their transfer value if they perform, meaning more revenue from academy sales.