"Itachi's war trauma was nothing special. Other characters went through the same and no one turned out like him, murdering his own family and traumatizing his brother for life." β seems to be a popular take among the antis, a very remarkable way to say they don't understand the nuances and are terrible at reading the text.
Canonically , no other other character sees war when they're as young as 4, but since wars/violence is very common in their world, it's safe to assume the characters witnessed it when they were too young to understand the significance of the events. However, in Itachi's case, it is repeatedly told to us that adults repeatedly exploited him for his nature and desire to not experience another war.
The other characters who are victims of war and are exploited to some extent are Obito and Pain, both of whom go on to causing much more trouble to everyone else, and have to be told "it is wrong to kill innocent people" to make them realise their pain is not more special than the others.
Itachi turns out That Way not only because of witnessing the war (that alone wouldn't have been the motivation for him to go that far) but because of the isolation that followed and lack of any solid support system, then grooming, and eventually his own family turning against him, until it was too late.
Denying his trauma doesn't change the fact that he was always an unwilling participant in every single violent act he carried. But you can't label him as a monster if you're also seeing things from his perspective.