I know what they mean, and it is an incorrect assessment with a great bias towards their own interests.
The boss is another role. You can be a boss. Why not?
Ah, it entails risks also: paying bills, managing, taking decisions, risk of going bankrupt... so when most people talk about expoitation they do not talk about the other side of things so that their complaints look legit.
Also, working in an already setup environment usually multiplies your productivity. But if it is not the case, then the natural consequence is that copying the business model and starting to compete should be an easy alternative. If people complain and do not do it, there are more reasons they are not talking about.
For sure there will be bad bosses, and bad employees, do not misunderstand this.
But if it is so bad and exploited you have other options: become the boss, switch job. If you do not want either of those, you should wonder why, not starting to insult people who give you the possibility to improve your life conditions or survive. Out of mutual interest, of course. Not bc they are saints.
It is very funny when I see people talking about how they are exploited by others and instead of finding an alternative, like taking the risk to invest their accumulated wealth, they just come with this discourse.
Remember that if you are an employee you can just switch jobs also, you can do something else, you can try to build something your own. What you cannot do is go with that discourse assuming the other part does not pay any cost: for example, when there is an investment, you have to spend a bunch of money for something that is likely (most business do) to fail, putting your money in advance. The people who work just work, leave and find something else.