Have you ever asked yourself why most successful traders either:
1) Trade OPM
2) Come from the Northshore of Chicago?
It is because the biggest impediment to making money in the markets is when you have to make money to fulfill some need. That need is usually economic, but it can also be a need to gamble etc. When you meet either of the two conditions above, you have taking your own money out of the equation, and the psychology is correct to learn the trade.
The biggest reason retail traders lose is because trading has to be about winning more than you lose. That the score is kept in currency, that blows up most people psychology. But what if the score was kept in rocks. What then?
Therefore, trade size so small that the money won or lost is completely irrelevant. Use this time to develop tremendous habits. Then when you get your real chance, your skills be they market skills or discipline skills or psychological skills will all be lined up.
So, retail traders lose because they jump at the deep and of the pool when they should be in the shallow end for at least three years. Probably longer.