Okay, this one is going to be short.
Many countries have laws about equal treatment for citizens and legal residents. These laws range from India’s Caste Disabilities Removal Act (1850) to the Inter-American Convention against Racism, Racial Discrimination and Related Forms of Intolerance (2013). These laws are generally known as anti-discrimination laws.
Many of these laws are meant to ensure everyone has equal access to employment and public services.
I do not know of, and my limited research can not find, any country or municipality where anti-discrimination laws protect poly folk. This means that the vast majority of poly and/or non-monogamous folk can lose their jobs or be denied a job, because of their relationships.
Potentially worse, some countries allow employers to include morality clauses in employment contracts. Depending on a country’s laws and safety net, if you are fired for violating a morality clause in your employment contract, you may lose your access to unemployment benefits.
Basically most people who are out or outted as poly runs the risk of losing their job. Even countries which allow polygamy may not provide protection against discrimination. This risk will be higher in some areas and some jobs than others. Anyone working for a conservative religious organization probably wants to keep their heads down. In the US, teachers are very much at risk of losing their jobs if outted. Sales people, less so.
Self employment, if you can manage it, offers some protection. Some people may refuse to hire me because I am out and poly, but no one could just take my business away from me.