Good point, and I think among a large number of recreational players (maybe a lot of serious players too?) very epidemic. You see it often, as an example, with the insults thrown by a player who gets sucked out, when the winner of the suck out had the right odd to make his call, and won that 1 in 10 pot which was why he/she made the call in the first place, and had the loser i.e. sucked out player made his bet correctly, the pot odds would not have been enticing the suck out player to call/raise. Then the pot loser, who had the best hand on the flop/turn, but played it wrong calls the pot winner a donk or whatever, when the correct play by said player could have caused a fold instead of a call/raise. This is an example of someone who cant admit his play was wrong, and blames the other players/site/fate/dog/weather for his "bad luck".
The suck out player had the confidence to play the odds, the sucked out player didnt have the confidence or the knowledge to raise enough to make drawing too expensive.
I think confidence is undeniably important, but it must be combined with the ability to say "man did I play bad there" when you did.
No, is not always easy to self diagnose honestly, but vital too playing a winning game.
And defining between confidence and loose playing is also important....
uhhh just read my own post, I am rambling on a bit here, hope my point is clear tho, havent had my coffee yet.......... water boiling, I am confident I will make more sense later.......lol