You're right, who in their right mind would want to return to a team where they treated you so badly? Even if it was the coach, the club should have plowed him and told him that's not how things are. Obviously, an Arab team has a lot of money, the one that's winning is CR7 and Saudi Arabia is at a level with its football. If he leaves the Saudi League, I don't think anyone will want to watch that league, that's a fact.
Ronaldo will not do something stupid like going to Manchester United again. First of all, Ronaldo is only 40 years old. At this age, going to a competitive league like the Premier League is the biggest stupidity. Secondly, Ronaldo went to Manchester United in the 2021-22 season. But the management did not give enough respect to Ronaldo. So why would he go to this club again? Thirdly, Al Nassr offers Ronaldo high wages and various kinds of benefits. I have a lot of doubts whether Manchester United will agree to pay such high wages. Ronaldo's fitness is good, but Ronaldo is still 40 years old now. Playing in a competitive league like the Premier League will increase Ronaldo's chances of injury. So staying with AL Nassr until he retires will be the best decision for Ronaldo.