I do not agree with the first point.
first even you have siginificant un-depletable capital, if you do not know how to use them to extract money from the market, you may do the reverse, keep flushing your money into the toliet. just like an army, if you are not a trained qualified general, even you own a powerful army, you may be defeated by a less powerful army, the only thing siginificant money can help you is: your psychology, nothing more than that.
as for the second point. I do not agree with it either. everyone can make money in the market by luck, even an idiot, i once hit the wrong button, I mean sell, but i hit buy button, kind of odd, I made money on that wrong key in error. diffenriate a professional trader from ameatur is: professional trade full-time, they own lots of experience (so they can gut-feel) , they own knowledge and the skill, and the strong psychology, so they can make consistent results, just like a well experienced well trained general he can defeat a war after another. welath built upon knowlede, deligence, skill, educatuion, experience...
Quote from Mecro:
You missed two key points:
They have significant CAPITAL and can afford risks you can't
They have a significant & often exclusive edge.