You see you move not often but when you move you make money big money gives you enough time to wait.
The above line helped me understand better what the OP was trying to make us understand, and I think I agree, trading with peanuts have never helped anybody I know(including myself) become a successful independent trader, so indeed OP is absolutely right.
For me personally, making at least $2000 as profit in a single trade can give me up to a month to patiently wait for another opportunity of making that same amount again or even higher.
~Snip~
Having the experience of losing will indeed teach us a lesson to be careful in trading so that the same mistakes do not occur. this will stimulate to achieve new capabilities and more effective strategies. But if you keep making mistakes without learning, of course psychology is the main problem why are you still stuck in the same hole. Knowledge is sufficient, but trading psychology is still not qualified and it's easy to panic. Even professionals will lose to an unstable psychology.
Though i dont quite understand what you meant, but let me tell you that psychology is we create for our individual selves by our individual selves , psychology is a believe we create from our experiences, knowledge of things, and sometimes, our background or where we come from.
This means that psychology can be changed, all it takes is for the right knowledge to come in, and the willingness to be open to accept and adapt to the new knowledge, this is how psychology, in other words, believes change.