You didn't answer my main question, also Hashirama and Black Zetsu were the only ones to ever defeat Madara and Madara said that the real winner is the one that plans ahead or something like that, he beat Hashirama after he came back and he never truly died.
Excuses. The one loss Itachi had in the entire manga was the time he let Itachi win. Madara though, he lost fair and square, and twice at that.
Itachi said himself he was a failure for not talking to Sasuke about the coup beforehand, that he had to do what he did is what people whine about, that is a failure to abuse your little brother and slaughter a group of people.
That's the whole "not working together with people" thing I mentioned...which is bullshit, not even in Naruto, you can't realistically expect the eight year old Sasuke to have the key to such an unsolvable political dilemma. It wouldn't have changed jack shit for the Massacre.
He never stopped Madara completely even though he released the Edo Tensei, he didn't stop Akatsuki when he was on the inside from doing bad things. He told Sasuke indirectly to kill Naruto. He wasn't the strongest, and I'm sure there is lots more, but not that I don't want him to be perfect I like him. But I don't think he is perfect. Why does that bother you though?
Because a perfect character is bland, and Itachi is bland, and the fact that people adore him despite the only thing stopping him from being a Mary Sue is the series' name being another character's. He's not the strongest, but he conveniently never lost, he didn't solve everything in the plot, but everything that was directly affected by him there was a success on his part. Everything.