Investing Psychology

There's a lot of things when you get into psychology. Investing is primarily psychology, right? Yes, you have to do the hard work, but there's so much of it that psychology, in your experience sych what are some of the psychological issues that come up when it most commonly affect investors? There are so many emotional issues at play, like greed and fear and despair, regret and confidence and over confidence and euphoria - sometimes even shame.