So since every coin I hold can be considered profit, by not cashing out I'm continuously making someone else lose, and will continue to do so until I do cash out? How can that be?
I'll tell you... the real losers are going to be those who stick with fiat until it is too late.
only if you are the exchanger or mining bitcoins your self.... if you are holding bitcoins their number is not increasing, if you have 100 bitcoins now, you will have 100 after 10 years, where will be your profit then? the only profit you can make is to take money away from other people at the right time...
It doesn't matter. You are not looking at a closed system.
It will only be a zero sum game if the exchange rate returns to its original value: 0.
Until that point (if it ever comes) we will have more winners than losers within bitcoin, and more losers than winnners in the fiat world.