It's about winning, but it's also about how you get there and with what money.
Consider this for a moment Claude: We invested £80 million in two - very good - starting players (Gabriel and Partey) this summer, and we're worse off in the table for it. We did the same thing last season (Tierney and Pepe) when we had our worst season in the era of the three-point system, and the year before (Leno and Auba) where both seasons ended in bitter disappointment.
Maybe the issue isn't that we're incapable of finding a good player every summer/winter, but that we don't have enough of them pulling in one direction at once. You have two ways of getting there: the City and PSG way, where you just buy everyone at once because you don't play by the same rules as everyone else, or the way of the rest, where you keep working with what you have at the moment while you create better pathways for players to emerge and grow.
Arteta is doing a 1/10 job this season with what he's got in the present, but that shouldn't affect Saliba's longterm whereabouts at Arsenal, at least not before he has been tested thoroughly and been given help to realise his talent. And selling him for half of what we paid right now is not going to get us to move up a tier any quicker.