People are not the easiest to understand. When it comes to the human mind, intuition generally causes us make false assumptions. This is not always a good thing as it leads to us perceiving order in random events; such as thinking you can predict a coin toss, just because you got it right last time.
This is where psychology is important.
Luckily, the methods and safeguards of psychological experimentation help us get around the issues caused by our natural tendency to be overconfident about our intuition. Using case studies, naturalistic observations, surveys, interviews, and experimentation, psychologists have, over time, produced some fascinating insight into the human mind.
From Crash Course: Psychology on YouTube presented by Hank Green