The government of Saudi Arabia needs to invest more in the league. Other clubs must be given the financial backing that would enable them to buy quality players from other parts of the world. If more good players are present in other clubs, the league might become more entertaining. The government should also make policies that would make the country's cultural and religious rules more flexible for footballers and football fans.
When the Saudi Arabians decided to shell out close to $500 million for Ronaldo (half of that for representing Al Nassr and the other half for being a part of the Saudi team that is bidding to host the 2030 world cup), they had two types of goals in mind - first one if short term, and the second one is long term. Short term goals include popularizing the Saudi Professional League around the globe and attracting more viewership and revenues. But the long term goals are more important. They want to improve the quality of football in Saudi Arabia, and make that country one of the top destinations for sporting events. And I guess that $500 million is approximately the right amount to pay, for achieving the second set of goals.
Saudi has not made a bad deal and they have spent millions and earned billions and got recognized globally all across the world
Ronaldo also feel happy to be in Saudi - his appearance is much celebrated