While i do admit Messi is more talented than Ronaldo you just cant say Ronaldo isnt extremely talented and claim that 90% of his succes is his hard work.
I completely agree with you, it's a complete myth that Ronaldo works hard but Messi doesn't.
To learn anything takes a lot of practice, to be good at carpentry, playing the piano, maths, science, dancing, acting, football it doesn't matter, it all takes a lot of practice, understanding and cognition.
Your brain forms neurological connections through pattern detection, exposure to a subject like driving a car, performing turns and gear changes frequently over days, weeks, months. As Cavemen we had to find patterns in nature and become good at making tools. Now we have to learn alphabets, complex language patterns, learning to operate a B52 bomber through specialist training, etc.
To say Messi was born with "talent" is ridiculous, someone that works in Starbucks might be the most "talented" footballer on the planet right now, but to everyone he's terrible, he can't even kick a ball because he has never played.
You come into the world as a complete blank slate, the notion of talent is absolutely absurd, maybe you enjoy something more because you are good at it, and you are slightly better than everyone else so your brain thinks "Hey I'm better than this person" suddenly you practice more than that 10% gap becomes a 20% gap and so on.
People get to be where they are being from the age of 3-4 they have a ball at their feet, they cognitively think "Okay, what happens if I try this with the ball? How do I get it to there? How can I beat my opponent effectively?"
Then there's of course external factors such as having the right environment, consistency, having good advice from coaches and being nurtured, but nobody can pretend Ronaldo plays football 18 hours a day and Messi plays for 3 hours and there's some magical force in the universe called "talent".
Pretty sure Messi has become really good at free-kicks and playmaking due to the way Barcelona play and plenty of practice, where-as Ronaldo has become a lesser dribbler and a better finisher because of his attributes, the Madrid set up and the midfield being so good as opposed to Barcelonas current state.
No matter what is said anyway people have confirmation bias anyway, you can say anything you like but if people blindly follow some rule like "Mourinho doesnt play youth" or "Don't eat carbs they are bad!" people blindly follow the information, ignore 9 pieces of information against that fact, but then get happy when one source agrees with them.
That's the world we live in though.
TLDR Ronaldo most likely doesn't work harder, or isn't any less "talented". Talent is a completely ridiculous word that means nothing.