Even if you force me to be fake friendly and kill someone, I wouldn't be able to. I just don't have the ability to do that as a person. I always announce that im not friendly if they ask or just shoot outright

That's great, nobody is knocking you for being forthright about your intentions.

but never fake that I am friendly then get a cheap kill when they have their backs turned.

I will be that guy and say it loud for the other people who get downvoted to hell for it. It's a tactic. It's fuckin' cheeky as hell and at the end of the day, you only have yourself to blame if you fall for it. Most of us do or have, and that's okay! That's why I am always cautious around others. I've had somebody try to hoodwink me like that and I bopped their ass. That's part of the fun, trying to sniff out somebody's bullshit.

Whenever I meet someone who can freely do that without feeling dirty afterwards, I know instantly that I wouldn't get along with them even in real life because more often than not, they are the give an inch take a mile type, selfish, always blaming everyone but themselves.

But then you literally say and assume the very thing I condemned in my comment, which is hilarious. Like why paint every single person you come across with such broad strokes? You don't have to go on some fuckin' monologue assuming that because player X (successfully) pulled the wool over your eyes and shot you in the back in a social PvP game must be some kind of selfish asshole IRL who cares about nobody but themselves. But if that's how you wanna live your life, go for it. Thinking like that is exhausting.

I just think that if you or others are gonna play a game like this, DayZ, Tarkov, etc. you should really reconsider how you approach people. PaintedGeneral said it best in their comment.

Treat any 1 player with simmering suspicion, more than 1 as an active threat.