I understand your point and hence said signing CR7 was the first step to make the Saudi leagues known globally, before that i never watched any of the matches nor had any idea about the teams but now i am following the entire league and signing big names is the first step and more big time players will be moving to Saudi as they have the money.
Ok but I think you are more of an exception than the rule. Watching the entire league and knowing all the teams because a 38 year old Cristiano plays there is not the rule. I assume that most people pay a little bit of attention, paid more attention in the beginning but now also realized that the SPL hasn't really changed. Ronaldo is there and even when there is drama I noticed on this forum that the discussion gets less significant. His club was closer to the top without him.
You need to understand that majority of the big English and European clubs are now owned by Arab countries like PSG, Manchester City, Aston Villa and Saudi's owned Newcastle United and Sheffield United. Common theme is that they have the money and if they are willing to give huge offers do you think that the young talents wont be signing with them. It is a long term plan and it is a matter of time that they start grooming youngsters like the rest of the European clubs and at the end of the day money talks and they have plenty of them.
Another aspect is that, you are just thinking about European Football fans, majority of the global population is in Asia and if they could attract the Asian crowd it is a much bigger audience.
I absolutely understand what is owned by whom and still one of the most valuable aspect of European soccer is the deeply rooted culture. You won't make baseball the number 1 sport in Europe and you won't make soccer the number 1 sport in USA. You can buy the fastest camels and start a camel racing league in Europe, but it won't go anywhere compared to soccer.
Soccer has already been the most popular sport in Saudi Arabia and yet it is where it is. Money can do a lot, but if you can't copy and preserve the culture it will unsustainable in the long run. A Saudi buying a club in Europe has more fun than a Saudi trying to build a European club in Saudi Arabia. Do the maths.
Your last point is about the Chinese Asian market and yes that is a very valid consideration. But there is still some cultural identification and that is why European players really never liked going to Chinese clubs because we are so different and that is ok. That is absolutely ok. We are more international and globalized, but you won't be able to import sumo ringing from Japan to Europe and have the people in Europe cheer as much for the sport as they do in Japan. What do you think where the Japanese professionals were to prefer to perform? Europe or Japan? If the money is big enough, they go to Europe, but it won't be sustainable because they grew up their whole life in a different place, inherited culture and attitudes and food and everything.
You can't just buy one Messi per team and say you have a great league. Just as an example, try to calculate what it would cost in salaries to build a 2015 Real Madrid and Barcelona in the SPL to at least have a clasico that the whole world will be watching because it is the highest quality soccer you can get from clubs. Then you need persistence, so let's say you build those two clubs and Atletico to keep it extra exciting and all three clubs for 7 years. Only salaries.