That is laughable list
Those players transfered to big clubs, but who became a star player? Which a talent like Adeyemi aspire for?
Sancho didn't prove shit, neither did Goetze(health was issue) Mhikitarian, Dembele, Pulisic were meh. Halaand and Belligham didn't even make that move yet.
Malen are more likely to be moved back to Eredivise than making a big move, he has the Luuk De Jong vibes in his Dortmund so far.
Non of those names became a star, what they did is moving to other big clubs which Karim has the chance to do now while skipping the Dortmund move.
Aubameyang is the only name who succeeded big time after the move, forgot about him. But he joined them at 24 and left at 28,and succeeded at Arsenal.
We can and will promise him a starting spot, there is really no argument there.
The pressure argument is fair, but then again it is also a question of what does Adeyemi wants?
Does he just want to play in big clubs? sure at Dortmund he will get the chance to do this later, with bigger pay cheque when it happens, but this is where it ends. And he can already make that while skipping the Bundesliga move.
Does he wants to be a star player? a ballon dor contender? Again, Dortmund never did that.
Pressure during development will happen sooner or later, if the kid trust himself he will opt for the now move.
And please, you keep saying players knows that but you still ignore that players and wonderkids still joing big clubs.
Vinicious, Rodrigue, Yussuf Demir, Emre Demir, other highly rated youngsters who joins Chelsea, City and Manu annually.