Yes playing with profit is a nice strategy like if we deposit 1 bitcoins and we win 0.1 then we can withdraw the 1 bitcoins back and just try our luck with the 0.1 which we have now. But this needs some will power as sometimes after loosing that 0.1 we move on to deposit the 1 bitcoin also.
Withdrawing your initial bankroll is not coming under "playing with profits".
Actually your way of gambling must be a secured one as you are talking about continuing gambling ONLY WITH PROFITS. But, here we need to consider, risking 1 bitcoins at first place and it is not that easy to gain 10% profits so hat we can withdraw our original capital. If it works then it must be a good idea, indeed.