Example of bad/negative role model: someone whose action (and its consequence) one should learn to avoid instead of emulating such as a gambler or robber.
The Opposite of a Role Model
People you don't want to be.
My wife worked as a technology consultant several years ago. She liked the job. She enjoyed the work.
Sort of, at least. One day she quit, abruptly and without much warning.
Nothing bad happened. No client ruined her day. No manager screamed in her face.
She just noticed that her bosses were miserable. They worked too much, rarely saw their kids, and always seemed stressed. They were nice people, but she didn't admire their lives at all.
Then she realized, wait: The career path she was on was specifically designed for her to become those people one day. That was the goal.
How do you stay motivated at a job where you feel bad for the people you're supposed to aspire to become?
ou don't. So you quit.
Nassim Taleb has a great quote. "People focus on role models," he says, "it is more effective to find antimodels — people you don't want to resemble when you grow up."
Also "bad influence" seems to fit.
While it can have a broader, neutral use, the term object lesson may suit
an action or story that teaches you how or how not to act, or that clearly shows the facts of a situation, usually a bad one: The disaster was an object lesson in how not to run a ship