In today's hotly-competitive marketplace, if you don't understand how to drive paid traffic and optimize your conversions, you need to turn to a company that does. The truth is that paid ads can get incredibly complex. Things like re-targeting and custom audience definitions, along with understanding the ebb and flow of everything with a sales funnel, is complex and confusing to most.
The ego is the driver making the decisions. It decides between the devil (the id) and the angel (the super-ego) on either shoulder (yes, all those cartoons you've ever seen are partly true). We have voices in our mind, and it's up to the ego to decide which one to fulfill. Its goal is to satisfy the id in some way while also attending to the super-ego.