Question for motorcyclists

First off, I will never get on a bike. Never. They look cool and fun, but for personal reasons, it will never be an interest of mine. I have nothing against motorcyclists. That formation shit looks cool as fuck. The loud noise doesn't even bother me. But I do question how some bikers behave in traffic. Being cut off isn't even an issue. What I don't understand is, while you're bobbing and weaving through traffic, going between lanes, squeezing through tight spots, while you may be confident in your riding ability, aren't you afraid of being the victim of other people's mistakes? When I drive, I always assume someone is going to something stupid, eg, I'll slow down at an intersection, even with a green light. You never know if someone on the other side is going to pull out on you. Defensive driving. It seems to me as if bikers have to be twice as defensive out there, yet it seems common for them not to be. Why is this?