The circular flow diagram is an abstraction of the economy as a whole. The diagram suggests that the economy can reproduce itself. The idea is that as households spend money of goods and services from firms, the firms have the means to purchase labor from the households, which the households to then purchase goods and services. Suggesting that this process can and will continuously go on as a perpetual motion machine. However, according to the Laws of Thermodynamics perpetual motion machines do not exist.[18] The First Laws says matter and energy cannot be created or destroyed, and the Second Laws says that matter and energy move from a low entropy, useful, state towards a less useful higher entropy state.[19] Thus, no system can continue without inputs of new energy that exit as high entropy waste. Just as no animal can live on its own waste, no economy can recycle the waste it produces without the input of new energy to reproduce itself. The economy therefore cannot be the whole. It must be a subsystem of the larger ecosystem.[18]
Under throughput analysis, the only factor that matters is the impact of a proposed investment on the ability of a business to increase its total throughput (revenue minus totally variable costs). Under this concept, the main focus is on either enhancing throughput through the bottleneck operation or in reducing operating expenses. This analysis requires a consideration of bottleneck usage by the likely mix of products to be manufactured, and their margins. This is a much more detailed analysis than is contemplated under the more simplistic residual income approach.
One of the things I'm surprised your article doesn't mention is the tax advantages of this type of investment. The depreciation and rehab costs (purchasing distressed properties) can be huge deductions to ones income taxes, which none of the others have. Then, along with the appreciation of real estate, this passive income investment outperforms the notion of maxing out my 401k as well.
Build an investment portfolio that pays out dividends (Stocks / Bonds / Mutual Funds). Dividends are payouts that companies give to their investors as a portion of their earnings. They’re often paid out quarterly. If you’ve already got an investment portfolio, it’s time to take a good look at which stocks, bonds, or mutual funds you own. You’ll see consistent returns from the ones that pay dividends. This is a fantastic way to earn passive income. Invest once and watch the returns pile up.
Greg Johnson is a personal finance and frugal travel expert who leveraged his online business to quit his 9-5 job, spend more time with his family, and travel the world. With his wife Holly, Greg co-owns two websites – Club Thrifty and Travel Blue Book. The couple has also co-authored a book, Zero Down Your Debt: Reclaim Your Income and Build a Life You'll Love. Find him on Instagram, Facebook, and Twitter @ClubThrifty.

Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.