One might characterize it as a hasty generalization.

A hasty generalization is a statement made after considering just one or a few examples rather than relying on more extensive research to back up the claim. It’s important to keep in mind that what constitutes sufficient research depends on the issue at hand and the statement being made about it.

“A rich person once created a job that paid less than greenman thought he should get paid, therefore, all rich people create serfs, not jobs [sic].”