what econ class did you take? that's not ROI that's simply getting your money, back, breaking even.
Breaking even means 100% ROI, no? Enlighten me.
Only in Bitcoin land. For some reason some clueless people started incorrectly using it that way and it stuck. For the entire rest of the planet ... in every other financial scenario ... no.
ROI is return ON investment. breaking even is 0% ROI. Losing money (like buying a 100 BTC rig which only produces 60 BTC before it goes into the trash heap) would be a negative ROI.