Answer: To be blunt, everything Tom Buchanan does and says in F. Scott Fitzgerald's The Great Gatsby confirms that he is a racist, abusive, arrogant cheater; even his wealth and family background do not save him from being anything but a villain in this novel.
He is a racist because he quotes from Goddard's The Rise of the Colored Empires and he believes every word of the premise: white people are inherently superior to black people. Thankfully there are no opportunities for him to actually display his racist attitude in the novel except in a conversation. Goddard's theories are outrageous and Tom was not the only one who believed this way, of course; however, it is a perfect picture of Tom's absolute, racist arrogance.
Tom is physically abusive twice in this novel. First, Daisy has a bruise on her finger which he caused; whatever he did was not crippling, obviously, but it demonstrates his lack of physical restraint with women. He treats his mistress, Myrtle Wilson, even worse. When she begins to taunt him a bit about Daisy, he slams her in the nose with his open hand, causing her to bleed everywhere.
His arrogance is apparent in the way he conducts himself, the things he says, and his total disregard for his wedding vows. When Nick comes to visit, one of the first things Tom says is, "I've got a nice place here." How absurd, backward, and arrogant of him to compliment his own house and grounds, something a visitor would normally do. Tom is disdainful of Gatsby because Gatsby earned his money, something Tom would never do. He is rich and spends his family's money on all manner of pleasures; he has never worked and never intends to. He boldly treats his mistress's husband, Tom Wilson, with scornful disdain, as well. Tom even has the nerve to include Nick, Daisy's cousin, in a party held in the apartment he keeps with his mistress. He has no shame but plenty of arrogance.
Finally, Tom is a cheater. The vows he made to Daisy are so meaningless to him that he cheats on his wife--with a hotel maid--on their honeymoon, and he is out with another woman the night his daughter is born. The Buchanans have moved quite a lot since they have been married because Tom's cheating always creates a scandal and they have to move to escape the gossip. He justifies his behavior to Nick:
