and there are many others that have come and flopped. There is a reason most promoted teams end up being relegated back after a few seasons.
You say he is better than Lucas and Lamela when all you have seen of him is against championship level opposition. A 21yr old lucas looked good in ligue 1 and a 20yr old Lamela looked good in Serie A, both leagues being much better than the chsampionship, but we all know how those two have turned out.
My point remains that there is no evidence, beyond your personal delusions, to support your claim that he is currently better than Lucas and Lamela. He might develop to be and he might fade away. That is not the kind of player we should be signing with our current squad problems.
Very few teams that come up are full of players that are as good as he is,
Really we don't ever know how someone will adapt to the PL so if that is your standard we will never replace anyone, What we do know is that Lamela and Moura are not good enough. They offer zero creativity, are poor passers and offer almost nothing in attack. It is a clear area that we need to improve.
Olise may or may not do that, but there is a much better chance that he does that than the two plugs we have that we know can't do it. He is also a guy that fills the HG quota which helps us a lot as well.
Being scared to take on young talented players is how your team gets stuck with garbage like Moura playing a key part of your season. It is a way you get passed by teams like Liverpool, West Ham and Villa who are playing young guys like TAA, Jones, Bowen, Benrahma, Watkins.
Teams that aren't scared to add talent and skill to their teams are having the most success, Teams taking your scared approach and despising skill fall off.