Adding to this. My first job out of college was with a con artist who is probably still conning people today.

There were contracts, everything seemed reasonable, and then the excuses for non payment started piling up. By month 3 I still had seen nothing. Even after a year very little had been paid. Years later, thousands of dollars still unpaid and just lies and excuses.

I still hate asking for money that's due to me and not getting paid for the work you did is a real shitty place to be. This person did the same thing and berated me when I said I would take legal action. When I did take legal action, their entire company was a scam and I couldn't even deliver a court notice because they were hiding out of the country.

Every time I see this person's name it angers me because I just want to metaphorically burn their business to the ground. When I blocked this person and erased them from my life, I became a lot happier. I took it as a learning lesson and developed an archetype for psychopaths to avoid. Some day they will get their reckoning but it's not worth my time or mental health.

Tl;dr: The impacts to your mental health might be many hours over years. It was for me anyway.