I hope he can retire with Manchester United, I know Ronaldo is not a money-hungry person because everyone knows the wealth he has made from football, but he is hungry for titles and wants to write a sweet story at the end of his career.
Ronaldo has indeed entered the era of the end of his career, his age has made his performance decline but it doesn't look like he will retire anytime soon, I think his desire to get the world cup trophy for his country is the reason for him to continue playing at this time, for club level Of course it looks like he will not retire at Manchester United because he previously said that he would end his career at his childhood club, Sporting Lisbon.
No matter how much you think Ronaldo has made, how much you think Messi has made or Neymar likewise, those guys are still concerned about what they recieve. They are not ready to do charity work with their career. They will always care for the pay. If they won't care for the pay, Messi wouldn't have left Barcelona and also Ronaldo would have reduced his pay to leave Manchester United this closed window.