so my intial investment was X and I hold Y coins and X/Y gives me $55.71.

you know what is the funny part, ok I still consider my self an early adopter, I didnt buy for lower than $1, but I bought a part of my coins between $10-15 and most between $80-120, but the funniest part is that I was trading and cashing out profits.

so if X is my initial investment and Y is the number of coins I hold and Z is the FIAT profits I cashed out this means X-Z/Y = ? if this is what you want to know, guess what, that gives me -700, which means that each coin I hold has already generated $700.

really interesting, I never thought about that, you made me think about stoping trading and not caring about the price dropping more....

Yes, that's what Pruden pointed out. If you made a profit in total, it it possible to sell coins to the point where the remaining (possibly fraction of) coins have a negative cost. That's okay, I didn't set up the question to make "gaming" it impossible, I was just trying to gauge where the forumites (or rather: the subset that votes) entered the game, approximately. Then again, the fact that I didn't mention you can have a negative cost shows I didn't really think it through initially.

I guess the whole simplistic way I asked my question really breaks apart for those who (a) daytrade a lot and (b) successfully so. Once you made a profit in total and cashed out more than your initial investment, the question really becomes more: "how much do you earn, per time x, by trading". So the question I asked really only makes sense for buy&holders, and more specifically: those b&h investors that didn't cash out their initial investment yet.