The third one makes a lot of sense to me. Though I think that the same forces operate with good: the more you choose to do good, the harder it becomes to do evil.

I think the majority of people go with the flow. So you can set up things to make it easy and rewarding and convenient to behave well, and most people will behave well. Set up things to make it easy to be a dick, and most people will be dicks. It's the outliers who have very strong convictions and will go against the social flow - in either direction. Everyone's an asshole sometimes and some people are assholes most of the time but serial killers are rare. Similarly, most people are reasonably decent unless there's strong social pressure to not be decent, but if you happen to be in Nazi Germany, most people are not going to be Sophie Scholl. But some will be.

In terms of actual human interactions, I think it's pretty useless to conceptualize "good people" and "evil people" as opposed to "good actions" and "evil actions" because most people aren't just one thing. That being said, I have met some sociopaths and my policy is to stay the fuck out of their way, because it's a bit irrelevant whether they are evil or jus doing evil, because they will harm you either way.