If a man invents the race theory, kills 6 million Jews, it does not mean that he is mistaken about everything in the world and cannot be, for example, a good father, friend, husband, etc.
I seriously doubt that Hitler
invented the race theory (that is to say "Racism"). Genocides have happened throughout history, even before the rise of civilisations (tribal genocide). Hitler did not even invent
anti-semitism. Anti-semitism has a long history going back to the early days of Christianity. But Hitler was mostly inspired by many 19th-century writers and the prevalent mood in Germany in the early 20th century.
As for his personal life, he seemed to have been loved by at least three women. In a documentary I saw about his life recounted by people who have known him, some witnesses explained that he looked so normal in real life that no one could have guessed he was chancelor by seeing him in the street.
It is also said that Hitler had a profound and deep love of animals, and he was a notorious vegetarian. There are reports of him disgusting his guests by giving them graphic accounts of the slaughter of animals in an effort to make them shun meat (surprising for someone associated with death camps !). He also had a habit to stroll everyday in the nature around his house in Bavaria. He was a rather reclusive and reserved man, who only opened up in the presence of people close to him. He was also a fervent anti-smoking campaigner before his days, and refrained from drinking alcohol.
So in many ways, he was some sort of role model for society in his private life. Even as chancelor he managed to make the German economy recover from the post-WWI crisis as well as from the world-wide economic depression starting from 1929. He reduced unemployment drastically and modernise the country's infrastructure. Had it not been for his social repression, warmongering and racist ideologies leading to the holocaust, history might have remembered him as a great leader and capable politician. It is undeniable that he lost most of his sanity in the late years of his life, but this alone does not represent his whole life.
In comparison Mao Zedong destroyed most of the country's cultural and historical heritage and caused the death of at least 5x more of its own people (30 to 40 million) than the number of Jews who died during the holocaust. Mao also caused the Chinese economy to plumet to its lowest historic level in comparison to the rest of the world, and to brainwash his people so well that it took several more decades after his death from old age for the country to start recovering.
Stalin cannot be said to have made of the USSR a modern and developed nation either, and his brutality far exceeded that of the Nazis. At least the Nazis treated occupied countries in Western Europe (France, Benelux, Denmark, Norway...) with respect. German troops were happy to enter into Paris, not just because of the victory, but because of the admiration and romantic feelings they had for it. German officers were often seen at the opera or other cultural events in France. In contrast, Stalin and Mao repressed both foreign and national cultures to levels never seen in a civilised nation.