I think it is the right decision to stay at Al Nassr. He gets enough salary, plays as the main striker and captain. He may not get these things again if he moves to another team.
Ronaldo is too rich to think about salary, AFAIK, he made a statement to make a new record, he wants to achieve a record of scoring 1,000 goals before retiring
if he not get injury for a long time. Until now, he scored 938 goals, if in one season he manages to score 35 goals they need 2 seasons to achieves. Maybe this is the reason makes Ronaldo to stay at Al Nassr.