@hjg suggest you watch these videos, paying particular attention to the last 2 in the presentation. Anton basically gives his view that the difference between Professional & Retail traders is that Retail traders take an income from their trading account whereas Professional traders (portfolio builders) re-invest to accumulate via compounding and take a minimal salary.
http://antonkreil.com/professional-traders-vs-retail-traders-101-media/
I would suggest in the real world of retail traders there is a suitable halfway measure, where you would take out a certain fixed value per month as a 'pat on the back' or 'progress' fee. Then use the rest of the capital to either bolster your trading account or spread the risk and open an alternative trading account elsewhere for different trades, i.e. use one account for day trading, and one account for swing/position trading over longer timeframes.