The life you describe sounds terribly lonely and depressing. "Can't trust anyone."
Funny thing is, when you trust people to *be who they are,* fears of betrayal go out the window. People are just people. The less you rely on them to be who you want them to be, the more you can rely on them to be their own selves. The blinders get ripped off, and people are just who they are: People. Run by their own fears and dreams, with their own insecurities and moments of pride.
As long as you ask people to change for you -- to meet your standards -- you'll be blindsided when they don't. And your attempts to control their behavior because of your standards will only breed resentment.
As long as you can see who they are, not what you want them to be, you'll never be disappointed. And you'll know how much energy to invest in the relationship, instead of hoping the energy you put in will be reciprocated.
Feel betrayed by someone? By your company? Ask yourself what convinced you that red flag was only pink. Because betrayal starts with believing something that wasn't true. And we see much better than we give ourselves credit for, if we accept what reality shows us.
That doesn't have to leave you feeling disenchanted or cynical, though. It's sad what knots people will tie themselves into to avoid dealing with facts. If anything it leads to feeling compassion, even if there's nothing that can be done to help them untie the knots.
So, sure, don't pretend your work relationships will go beyond the time you work there. But that doesn't mean they aren't worthwhile relationships. Everything changes. Everyone dies. But this moment can be as cynical or as magical as the baggage you carry. Even if, in this moment, you're working.