The BIG reason fix + flips are much closer to an active income (via business) than passive income (like rentals).
From Equity and Loan to Value to Cash Flow and ROI. Learn the key terms us in investing.
Using the above formula, you can calculate what total rents SHOULD be to hit a desired cash flow/unit on any given property
ROI looks at the total return on your investment, analyzing the real estate trifecta (noted HERE) of cash flow, debt paydown, and appreciation.