I think it's part of the way we are socialized into a society based on economic competition. So it seems normal to us, but it's just another way of saying "it's not perfect, but it's the best/only system we have!" as conservatives are so fond of saying. I don't think it's hardwired at all, but we're intentionally taught that it is.

I took an anthropology class once and learned that there's archeological evidence of early tribes taking care of disabled elderly (for the time) people. It would have taken a lot more energy to take care of a disabled person in a hunter gatherer society than it would now. I feel like a capitalist would have just left them to die in a cave because that's what Ayn Rand would have done.