Am I a bad person for being nice to my boss who screwed my co workers, and I over?

In 2014 I started working for landscaping/plant nursery. Everything was fine until 2017. My boss started paying us later, and later. Until our payments were 2 months late. Lots of people quit. Even the managers. I finally gave my two weeks notice in the summer of 2018. I was straight up with my boss, and told him that I don't want to deal with getting paid late anymore. Well, there was a large forest fire near where we live in 2017. There was ash everywhere. My boss tried telling me that because of all the ash that our plants weren't healthy, and there was no money coming in for that reason. It may have been true but I wasn't buying it at the time, so I just quit. In 2019 I was desperate for work so I started doing landscaping for him like 2 days a week. He paid Me under the table. I then got a real job, so I stopped working for him. He still owes me $600. I see him around often, but I never brought it up. This is where I think I might be a bad person. We've had a few conversations and I was very friendly with him. I even wave to him everytime I see him drive by. I'm just nice to everyone. That's just who I am. I feel kind of bad, because he may think that me being kind to him is an okay for him to do what he did to me. See what im saying? It's just really hard for me to be mean.

Am I a bad person for being nice to my boss who screwed my co workers, and I over?
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