Those who choose to focus on passive income will need either family money, funds from investors, or the nerve to borrow large sums by taking on debt to fund the purchase of assets. Consider someone who takes out substantial bank loans to build an apartment building or buy rental houses. Although this can turn a very small amount of equity into a large cash flow stream, it is not without risk. When using borrowed money, the margin of safety is much smaller because you can’t absorb the same degree of setback before defaulting and finding your balance sheet obliterated.
In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.