Most of the time, greed really push you to change the direction of your plans, there are position which you already reached your target but instead of stopping you choose to keep trying to earn more, and in time that the direction of the market turns against you, that's the time that you really regret why you choose to stay instead of quitting and withdraw the money that you supposed to earn.
Exactly, greed also can make you not to accept the initial profit that you must have already earned. Greed can make the trader to overstay in a position that they are supposed to have exited and take profit first profit but because they are expecting a huge profit, they will not exit the trade until they lose the first profit. Greed can make the trade to use a big lot size or a leverage size.
And like what I've said it brings regret after, upsetting your own position mostly happens either you overexcite yourself with the market movements that influence greeds inside you, though some traders manage to work well dealing with fluctuations and they really love volatilities and some successful traders has been motivated by success and how they keep working adding knowledge about the market and makes them more profitble along the way.
I agree that it usually doesn't end well.
Only through experiencing bad situations and climbing out of them learning something new and how to avoid them can a trader become better in what he does.
That's my opinion.
Exactly if after failing you bring that learning experienced to do better, that's the time where you can possibly developed your knowledge and will give you hints when to position yourself, though it's not an assurance but can be use as basis of potential similar outcome that may take place, from that point, your anticiaption will grow and you will start to aim for more knowledge while you are in the process of establishing your own patterns and strategies, all will be concluded after you begin earning your success.
If bad outcomes gives you the will to continue imporving yourself, and instead of living with regrets but moving forward with better outlook for your potential success that's a kind of motivation that will lead you to become more reliable and will possibly bring you to the position that you are aiming for.