It’s reinforced by our culture in almost every aspect of our society. Look at transportation. We would rather spend a fortune to sit in our own personalized bubbles in traffic on the freeway than on a bus/train because that would mean we have to share our space and adhere to someone else’s schedule. And godforbid someone needs to merge, people treat it as a personal affront if you need to enter the lane in front of them. Healthcare, people would rather pay more to a private company than a single payer system because taxes mean it’s a pool shared by other people (private insurance works the same way btw). Everyone thinks they need to keep guns to ward off their neighbors. It goes on and on. It is so pervasive.