Presently, there’s only one factor that makes Saudi clubs being, in a way superior and that’s in the case of funding. With their extremely deep pockets, they could try and entice any player they want into coming over to play. The issue of funding is a very important factor but that alone cannot even begin to make it superior.
Don't be jealous.
It doesn't seem to be a matter of jealousy but because the Saudi team has a large budget and is able to buy and provide large salaries for top European players it can make it difficult for European teams to recruit players in each transfer season because many players are starting to be more interested in joining the Saudi team.
It is not surprising that several European coaches have submitted suggestions to FIFA to regulate player transfers because it can also be seen that the development of player transfers for the Saudi League is superior compared to the European League.
If the players want to move from UEFA leagues to Saudi Professional League, then they have solid reasons to do so. I agree that money is definitely one of the considerations. Obviously in the recent past, UEFA clubs used their deep pockets to steal American, African and Asian players. Now Saudi Arabia is giving them a taste of their own medicine. Overall, quality of football in UEFA confederation is on the decline (would make an exception for France and England). And once the star players depart from their leagues, the quality will go down even further.
The only main reason is that the money factor is large even far above the ability of European teams to provide player salaries but on the other hand the Saudi League is easier to get the championship trophy and is different from the European League which clearly competes strictly.
For example Ronaldo managed to win the title in just one season.