Most people when they think of psycho think of someone irritable, loud or overreacting. This couldn't be further from the truth.
Psychopaths are usually extremely confident, charming and can make great impression on people. Psychopaths major difference from ordinary people is total lack of empathy towards feelings of other people.
When an ordinary person sees suffering of another person he/she also feels the "pain", but psychopath doesn't feel it. Not only the pain, psychopath doesn't really feel shy or fear, that's why they look so confident and charismatic in front of people.
Some people say that Steve Jobs was a functioning psychopath and so is Tom Cruise.

Here's an interview of a functioning psychopath.

https://youtu.be/bdPMUX8_8Ms