Saudi Pro League has lot of money which gives them advantage in signing players. If they join competition European teams will have hard time getting players they want. Antonio Conte wants Lukaku but Chelsea won't sell him cheaply or easily. If Napoli lets Osimhen go it means they want to rebuild their team with Conte. After bad season with three different managers Napoli can become strong team again next season. With Conte in charge and focusing on Italian games Napoli can compete with best teams in Serie A again. It won't be easy for Conte but he has the skills to help Napoli improve.
Conte's desire to bring in Lukaku could indeed be a wrong option because Lukaku still has the instinct to score goals. But Conte also has to look at the options of several other players whether it would be very suitable if Lukaku were brought to Napoli because Osimhen himself is still not certain about moving from Napoli to another team. Although most people probably believe that Conte can bring Napoli back to compete with the other top teams in Serie A next season.