In my experience, people who are assholes in small ways are almost always also assholes in very big ways as well; they just don't know it. They don't have a strong ability to reason ethically and consider the risks and ramifications of their actions, so instead they learn a lot of social rules (e.g., it's wrong to steal, it's wrong to hit women, etc.) and think it means that they are a moral person where it matters.
However, when good behavior or bad behavior is not directly spelled out to them like that, they cannot easily differentiate between them and often select the bad behavior.
When I meet someone who is an asshole in small ways, I quietly put them on the list of people I do not trust or respect. I make sure they do not know I feel this way about them (due to not trusting them), but I take steps to undermine their ability to do harm in the world: I subtly discourage mutual friends from becoming close to them, I subtly push against them being promoted into managerial positions, I subtly warn friends who have crushes on them, etc.
However, when good behavior or bad behavior is not directly spelled out to them like that, they cannot easily differentiate between them and often select the bad behavior.
When I meet someone who is an asshole in small ways, I quietly put them on the list of people I do not trust or respect. I make sure they do not know I feel this way about them (due to not trusting them), but I take steps to undermine their ability to do harm in the world: I subtly discourage mutual friends from becoming close to them, I subtly push against them being promoted into managerial positions, I subtly warn friends who have crushes on them, etc.