Answer:
Psychology has been able to identify the mental problems man goes through. Without it, a lot of mental issues that you or someone you know is going through would be unidentified and left untended which could lead to serious issues.
Example:
Lets say someone you know has bipolar disorder. You would think its just severe mood swings and erratic behaviors, when in reality, its a serious mental health issue that psychologists have been able to identify and make medicines for to help subdue the symptoms