Because we didn't evolve to be rational. We evolved to reproduce as often as possible, not to thing as precises as possible. We're not thinking machines, we're

Because we didn't evolve to be rational. We evolved to reproduce as often as possible, not to thing as precises as possible. We're not thinking machines, we're reproduction machines. That we are able to think somewhat rational-ish is only because we adapted by adopting extensive modeling simulations. The fundamental function of these simulations is to simulate other beings, primarily human. And in that our brainware is lazy as hell, because - to quote evolution; why do perfect, when you can do good enough? Saves a ton of energy. The wetware we employ was never expected to rationally solve differential equations or do proper statistical analysis. At best it was expected to guess the parabola of a thrown stone or spear, or empate the best way to mate without facing repercussions from the tribe. So, really. It's not that thinking is hard. It's just that we're just not equipped to do it.