Yea well people shouldnt do that
The truth is that human beings don't work that way and never will...humans are imperfect beings. We're actually all assholes...it's just that some of us are more upfront about it.
The sooner you realize that the world is not a nice place and that people WILL fuck you over if you let them, the sooner you can prepare for that inevitability and begin to build up your defenses and immunity so you can better protect yourself.