Donquixote Doflamingo’s reasons and motivation
His motivation is unexpectedly noble for a guy who has suffered brutal violence and was raised by the ruthless killers. We can look into his head for the first time when he has an emotional outburst over the situation in Marineford. When Doffy’s emotions started to outpour, he verbally attacked the World Government.
海賊が悪!!? 海軍が正義!!? そんなものはいくらでも塗り替えられてきた…!!! // Pirates are evil?! The Marines are justice?! Such things have been changed as many times as you want!!!
“平和"を知ねェ子供共と"戦争"を知ねェ子供共との価値観が違う!!! 頂点に立つ者が善悪を塗り替える!!! 今この場所こそ中立だ!!! 正義は勝つって!? そりゃそうだろ! 勝者だけが正義だ!!!! // Brats who don’t know peace and brats who don’t know war have different values!!! Those at the top decide what is good and what is evil!!! This place is neutral ground right now!!! Justice will prevail, you say?! Of course it will! Whoever prevails is just!!!!
A huge inscription "The Marines” that is shown when Doflamingo is talking about the nature of justice kinda implies.
Justice is the favorite word of the Marines, the World Government army. He directly accuses the Marines of being not very just and defending the world order that brings people suffering. In the pictures from his head, the different values he mentioned are illustrated by the attitude to food. The child soldiers are happy about the canned food they have found (if there were meat on the skeleton, they would probably have gnawed it too), and the rich girl does not want to eat vegetables. Why this particular example is given becomes clear later.
These are the elite officers of the Donquixote Family as children. As can be seen, they all were destitute. The rest of the Donquixote Family members as children are also depicted in a similar way. Doflamingo felt like saying pirates are not always evil and the Marines aren’t always this shining beacon of justice, because sometimes piracy is a lesser evil than…
妻が焼き殺された…!! どうでもいいんどろお前らにゃ // My wife was burned to death!! It’s nothing to you, right?!
お前らに納める[ 天 上 金 ]のせいで…!! 国が飢餓で滅んだんだ……!!! お前ら腹へったことあるか!? みんな骨と皮になって死んだよ!!! // Because of the Celestial Tribute we have to pay, the country has been ravaged by famine!!! Have you ever had nothing to eat?! Everyone died leaving only a bag of bones!!!
...than death from starvation.
At the time of the Marineford Arc, it was not yet fully revealed how terrible the rule of the WG is, but, to put it bluntly, it turned the world into a giant Nazi camp.