Just a clarification about the much used term ROI (return on investment). I just want to make sure everyone's talking about the same thing.

Someone told me the other day that they had bought some hash contract for let's say 1BTC. It is not transferable or resaleable.
Its only value is its projected earnings. He was very happy to tell me that, over 4 months, he had cumulatively received back in small payments 1BTC and that his ROI was 100%.

I have a conventional fiat business background and said no, your ROI is 0%. The 'asset' that you paid 1BTC for has no fungible value so it is a -1BTC on your balance sheet, which also contains a +1 from your earnings, equalling zero, which is the ROI you would have if the contract stopped paying now.
Up until break even, you are just receiving your own money back.

No need for any abuse here (probably get it anyway), it's a serious question because I can see some newbies seeing claims of 150% ROI meaning 150% profit.