Because human are all the same

Be it a passionate young Nick Leeson, or a family man Rusnak of Allied Irish Bank, they are all human. And human are all the same. Human has emotions. Human has creativity. Let alone the creativity be used when developing a system. And the emotion be the motivator for developing a better system. But when trading a live account, let the system run itself with 0% emotion and creativity. That is why great successful traders use 100% mechanical trading systems.