I’m sad to hear that is your experience. Perhaps find an employer who wouldn’t treat you like a slave if legally allowed?
Are you wealthy enough to stop working entirely? If not, you (and most of us) are a slave to the system. Yes you can choose to change employers, but you cannot choose to stop working if you want to eat, have a home, electricity, etc.
Employers are not your friend. They don't pay you because they're "nice people".
I feel you’ve been involved in some exploitative workplaces in the past that have pessimistically shaped your view of business.
With that being said, I’m still youngish and I’m probably naive. Maybe I’ll become a jaded capitalist too when I’m older.
You misunderstand. These employers/managers/etc can be decent human beings, but at the end of the day you are a resource to be utilized to further their goals in exchange for an agreed-up sum of money. As long as things are going well, everything's great for everyone involved. However, if/when things start going sideways - for example a round of layoffs are needed, they're going to make hard business decisions based on what's best for the company - your personal situation/needs will not be taken into account.
Don't mistake professional behavior and cooperation at work for friendship. They're not your friends.
Paying someone to be your friend always makes for an awkward relationship.
I don't think it's a pessimistic view of business. I've always felt this way.
Businesses view people as resources. When resources are in high demand, companies compete for you and thus must try to make/keep you happy. When supply is high and demand is low they can and will make lowball offers and make unreasonable demands like working long hours/weekends/etc.
I've worked for good companies and bad. The bad ones always tried to make you feel guilty for not putting in the extra effort. The good ones make you feel like family. But they're still companies with one core mission: grow and make someone more money.