Buying at the top and selling at the bottom

Could someone try to explain how I always do this? I'm genuinely trying to understand the psychology of how I keep doing this. I mean how does this happen so often? I could literally wait and wait and wait and then buy and it immediately goes down and finally when I cant take anymore pain I sell and it immediately goes back up. How am I the only idiot that keeps doing this? How do you know its the top or bottom??? Am I just that unlucky?