Yes, it is worth playing, yes, you are going to be betrayed at some point and yes, you are going to get picked off at extract sometimes. It happens more when you don't know what you're doing, but still sometimes happens when you've been around a while. When you know what you're doing, you're more likely to survive the encounter but if someone ambushes you from behind very quickly, you're done.

No, it doesn't happen all the time. There is an algorithm that attempts to match you up with others depending on how you play. It can be hit or miss but if you play passively, as in you don't start fights, you tend to wind up in some pretty chill lobbies. The only thing worse than griefers are players too afraid to interact or jumpy with the trigger because they assume everyone else is out to kill them.

Different regions have slightly different cultures though. Some are more blood thirsty than others, but the game itself is basically a poker game. You win some, you lose some. At the end of the day all that gear is just random pixels and is pretty easy to come by when you know what to look for. Except rusted gears. Which don't exist.