Surplus value is the value created by labour over and above the amount required to reproduce that labour. It is an intrinsic quality of human exertion, and has been present throughout history: it can be invested socially towards collectively agreed goals, it can be acquired by force by a feudal lord, or can be extracted through the process of production by a capitalist employer. Because of this, most businesses are immoral in nature. They will say things such as “but I took a risk” in order to justify underpayment of their workers. Similar to a parasite, they suck up all the surplus value of a worker to thierselves. How are they allowed to do this? Because they abuse their advantaged positions against those that are poor. They aren't desperate for food, so they're not forced into positions where they are required to work for those that pay them less than what they're worth just because they don't have access to the means of production. Most business owners are evil, for this reason.