Because that's your opinion and not an actual fact. 8-4 in leagues, 4-3 in League cups, 4-3 in UCL while still being 2 years younger, Leo has almost every record bar the UCL one that Ronaldo took from him and has a better goal per game ratio. Portugal wins a EC and that automatically turns it around for Ronaldo despite the fact that Messi has managed to play 3 international finals and won a Olympic gold medal? Suit yourself but that's not objective and I won't abide to that, just came to express an opinion
And of course, you can say that's because Messi has played in a great team (Like Utd or Real were pushovers when Ronaldo played there) but even with that, Messi has won a good part of his titles playing against Ronaldo, that can't be so easily said about international competitions.
And I won't say he doesn't deserve his titles this year as if it wasn't for him Madrid would likely fall against Wolfsburg and he played an important part this Euro, even not at his best 60 good minutes from him spared around 7 games did enough to put Portugal in the finals, I just want to defend an honest and fair "fight" against Ronaldo and Messi