Getting into trouble with the law, doing unsavory acts, developing a substance abuse problem or even going behind the company's back to bad mouth them on social media is a quick way of getting fired.
And should said actor take a role in a production where they'll do things like nude scenes, using foul language or engaging in criminal behavior, then will arise against that actor for or somehow.
Among the things Culkin's character does are killing a dog with a homemade nailgun, causing a highway crash by dropping a dummy off a bridge, attempting to kill his mother, and as it's later found out, murdering his younger brother by drowning him in the bathtub.