Profit is a more slippery word than ROI, but in financial jargon (which ROI is), it does not equate to profit. POSITIVE ROI is profit. ROI is just a measurement of Return On Investment. See the OP, he explained it simply but perfectly. This has been driving me nuts since I first started reading this forum.
If y'all used the correct term, breakeven, you wouldn't cause people like me (and presumably any other person with even a hint of finance or money management experience) to have a rise in blood pressure every time they see "my miner won't make ROI".
There are truly only two scenarios where a mining machine will not make ROI, both rectifiable.
The first is a personal problem. Due to your fears or apathy, you don't plug the damn thing in. It will certainly not make any returns on investment in that case.
The second is a dead unit, easily rectifiable even if you built it yourself. You fix it, or you get it replaced or repaired. Then it will make a ROI.
Now, if you had instead said "My miner won't break even", you at least have a basis for rational argument. The "words evolve" argument is simply sloppy. ROI is an abbreviation of a VERY SPECIFIC term within a very rigid discipline. It is not vernacular, and you won't find it used the way it is here anywhere else. For the first couple of weeks, I found it confusing as hell before I realised that non financial people were bandying around a term they either misconstrued or did not understand. In any particular discipline, words have very specific meanings, and not knowing those meanings is something that sows confusion and doubt, often deliberately. For a good example, watch how creationists will constantly state that evolution is "just a theory" as if theory had the meaning of a postulate in the sciences, instead of it's actual, specific meaning. That case, at least, could arise from a "vernacular" use, in which a theory is actually just speculation (though even in it's vernacular theory implies the scientific definition e.g. the best explanation for the available facts). In the case of ROI, even that excuse don't hold water. It's a very specific term with a very specific meaning.
To the OP, thanks. This is something that twists my brain, and I'm glad it has a thread to point to, because I keep getting jumped when I point out what should be obvious.