This is one of Poker's great mysteries, I think it is all down to the individual player, Over a life time of playing Poker a skillful player will win most of the time, while a lucky player will win some of the time. It's called Variance!
We all have faults and make mistakes, but Poker is a game that is won, the majority of the time by players making the fewest mistakes, and like it is often said " you can pick up Poker in 5 minutes, but it takes a life-time to master".
A player who spends as much time studying as they do playing, will better their chances of making fewer mistakes and become more skillful and successful, when playing the game. I usually spend more time watching Videos and professional players playing than I actually play myself.
There is nothing wrong in that, as I feel my game play has got a little better over the years and yes I am winning overall when I sit down for a session. I may not ever win a World Title but who cares?
When the fun Stops, STOP!