An extremely large number of writers mishandle psychopathy/sociopathy, which is probably why the world is a lot worse than it should be.
They tend to make "psychopaths" to be mustachioed types that look sketchy or oily from the start, have a wicked laugh, and are so reeking of evil that everyone can tell. Or they make fun of people who have trouble expressing their emotions (like Maytag, when she's not doing her dramatic dual personality). Or they decide people who hear voices or have weird behavior are psychos (this one really annoys me, because it means autistic ppl and scizophrenics get feared and/or mistreated).
The person on the bus that you should sit two seats away from isn't the smelly woman who mumbles to herself "ash nazg durnatuluk, ash nazg gimbatul..." not unless her eyes glow or head turns backwards. It's the charming "confident" guy or girl who seems to have no sense of restraint. This is a warning sign of about three dangerous social disorders: sociopathy, psychopathy, and toxic narcissism. And you will later discover that lack of restraint also means lack of remorse. If something bad happens, it's someone else's fault, or some excuse. I believe Kohlberg was right, that there are stages of ethics. The psychopath, when written correctly, is someone stuck at the preconventional morality, they avoid punishment. Now, how many politicians does this sound like? If you said, "All of them" you're unfortunately probably right.
I find the D&D idea of good/evil overly simplistic. It's too much like the melodrama with eirher ppl in mustaches or people with chainmail armor and swords and shields. It also fails to account for complex motivations. Except there are nine instead of two.
Law, Balance, and Chaos is the model of Avatar: The Last Airbender, Korra, and some other media. The difference between this an D&D model is that chaos doesn't necessarily mean crazy as you can also be lawful and crazy (as Kuvira was), and good and evil are the result of actions not the cause of them. That is, you don't do things because you're evil, you do things because of personal motivations, and if suffering results, you're out of balance and something evil has happened as a result of you. Keep doing evil things, and it makes you an evil person. Not the other way around.