Ronaldo is already old and might have a good reason why he doesn't want to partake in the club world football and I don't see anything wrong about his decision. Of course, experience in needed in football much more than strength because lack of experience can make a player miss his opportunity of scoring a technical goal.
Things are really strange to see that CR7 doesn't want to play, he already won the Nation League, he left many people speechless at how a 40 year old man beats a 17 year old boy, you can see his power there, besides it would have been crazy if CR7 had played because he would have sold a lot, and that was what Infantino wanted,
but since FIFA has always been so inconsiderate with the best in history, CR7 pays them like that.It's no longer news that fifa and the rest of the footballing bodies no longer care about the welfare of the players, they care more about the money they stands to make commercially than if the players is burning out or not, and it's a good thing that cristiano Ronaldo prioritize his health over any amount of money he was going to be paid if he had agreed to partake in this club world cup tournament.
Though you are actually right when you said that they might have sold a lot if he had agreed to partake in the tournament, but it would have
bebeen detrimental to his health as a player, especially for a 40 years old, so thumb up to Cristiano Ronaldo for choosing his health over anything else.