As anyone who has mined knows, calculators are absolutely terrible at predicting ROI.
Historically the best priced hardware has always been able to ROI regardless of how many people "proved" it couldn't using calculators.
That best kept secret in mining. The second best secret is just how well you do when you sell your old equipment on the secondary market when you are done with it.
Buy a unit for $500-$600, mine a coin out of it, and then sell it for $300. Happens every single day.