There is no fixed ROI you will get. BDD is a zero sum game (minus the fees). That fact that you started calculating a ROI means you will have to re-read the OP.
All this reaction from you over my stating what B.EXCH returned over the past 30 days. Must be completely utter news to you as you've never done spreadsheets on anything before. HINT: Openoffice plus high school math skills.
If B.EXCH lost 50% of your btc over a month, would you "play the game?" Course not.
If B.EXCH returned 8% profit over the last month as I've calculated, would you "play the game?" Maybe yes.
Just settle down. Sounds like 20's is your guru or bosom buddy of yours.
So what.
There is no fixed ROI you will get.
But you do get a ROI, else why play? Again, this deluge from you is because I did some work and showed that B.EXCH returned 8% for the last 30 days. What is so wrong with my stating that?
BDD is a zero sum game (minus the fees).
The NYSE is a zero sum game too. Again, what exactly is your point? That no one is really making money off B.EXCH ? I doubt that...