Cristiano Ronaldo's arrival in Saudi Arabia has not only improved his team, but all Saudi teams. That's why I think his arrival in the country is a great opportunity. He may not have won any trophies with his team, but he instantly elevated the country's football reputation. So, what he's done is invaluable.
The popularity of the Saudi Pro League increased drastically after Ronaldo joined Al Nassr, and I think for that reason, they are still keeping Ronaldo, even though he's no longer young. Al Nassr hasn't won a trophy yet, but Saudi initial goal of recruiting Ronaldo seems to have been realized, and maybe this season Al Nassr will succeed in winning the trophy.
Overall, the PIF has laid a strong foundation for their long term goals, with Ronaldo, the Saudi Pro League has become better. I think former top European players have the courage to move to Saudi because they see Ronaldo, which means Saudi can also offer a good environment for football, even if it's not as competitive as the top European leagues. Of course, the main attraction for them is money, and that's actually also generally true in Europe.