This is a field of money and when they are already very difficult for big clubs in Europe, there is really nothing wrong with moving to a place where at least even though the competition is still minimal, there is no doubt about salaries and facilities.
On the other hand, even if it's like that, the Saudi Professional League seems to have its own targets for this and indeed it is proven that by bringing in some big players like Cristiano and now there is Benzema, Kante and even the news about Zaha who will be attending this will obviously make them more able to impact in terms of popularity because regardless of anything this is also quite important for them.
There is a strategy behind their approach and I think for now it is most likely about drawing attention to the league, to increase the popularity of the league and to make the Saudfi Professional league more attractive as a commercial market. But they do need to increase the global authentic audience. People who follow the league not only because of one single star player, but because of growing interesting competition. Whether that can be achieved this way is hard to tell, but their next step will be to bring in younger players as well who actually become central figures to the league. They don't only want the old Ronaldo. They would rather want the young Ronaldo develop in their league and simultaneously grow a fanbase that pertains primarily to the Saudi soccer league .
Surely they are looking at it as a promotional event for their league so that it is more popular and known in many countries. Like when Al Nassr succeeded in bringing in Cristiano Ronaldo, for example, they were fighting for the broadcasting rights of the Arab League and that was clearly the advantage they got. And I'm sure most of the people discussing here were initially not interested in the Arab League, and I can't deny that it was one of them.
Star players have their own charm, especially if they have a very large fan base in a foreign country, and when they come to a place the fans will go there.