Folks can bring up a various numbers of dictators who justified their greeds, but each one wasn't for the good for their people overall.
Not to envoke Godwin's Law, but just take Hitler for example. He had a vision of a "Thousand year reich". He had an idea of what he thought was right. But both flies in the face of universal truths of "do no harm". He executed his own people for simply being different or disagreeing with his policies. Just disagreeing or being different isn't justified for killing (or in this case murder). No matter how he could justified his aims, he was morally bankrupt after violating the universal morals/truths.
Those universal morals/truths defy even dictators, because they must harm and control those morals/truths to not be a pariah of society itself (and society getting rid of that pariah for preservation).