It wasn't about who is currently the most popular athlete on earth, the discussion centered around the question who was the biggest sports star ever. So of course he is up against Jordan, Ali, Federer, Pele, Maradona etc. and those seem to have been more influential than Cristiano. And as you see in the Forbes list, there is quite a bunch of current athletes who earn more from endorsements than Ronaldo. It even seems like Beckham in 2012 (37m) had higher endorsements than Ronaldo in his best year (35m) despite inflation. It isn't even that important, nobody is denying how enormously popular Cristiano is (definitely number one among footballers).
As I said, you really think that every 16th human being on this planet is a Cristiano Ronaldo fan? I am not talking about knowing him, you claim that this many people are fans of him. If you take out elders above 50 and children below 5 you are probably close to every 10th person and that doesn't even exclude the vast majority of the world's population that isn't even interested in football at all. The 2014 WC final had approximately an audience size of 1.1 billion. Not even a 7th of the worlds population watched the world's biggest football event. Even if you double that in order to estimate the market volume of football you claim that every fourth football fan would be a fan of Cristiano Ronaldo. At least your common sense should tell you that this is bullshit. I think you have no idea of the numbers you are talking about.
And no, your estimation is not perfectly reasonable. Again, you are basically claiming that Juve's net profit margin is higher than the gross profit margin of sports article retailers (which also sell online, by the way). We are talking about a decrease from 30-37% gross profit margin to 0.8-1.5% net profit. Yes, if Juve counts completely on online sales their fix costs may be much lower but, do you really think the net profit per unit of Juventus Turin, a company which isn't even specialized on E-Commerce to say the least, is approximately 40 times higher than the ones of regular sports retailers? Come on. Nobody is denying that Ronaldo will make them lots and lots of money or that they profit from handling their merchandise autonomously thanks to him but 40% is just completely out of scope if you consider costs for marketing, logistics, personnel, infrastructure etc.