The bottom line is, it’s smart to have multiple income streams no matter who you are. Why? Because the more ways you can earn money without compromising your integrity, the better off you’ll be. And if you’re self-employed, having multiple income streams is almost essential. Not only will you enjoy a higher income, but you won’t go broke if one stream ends out of the blue.
For example my business is a LLC taxed as a S corp. I am active in it and my wife is not. She owns half the company because she fronted the money to start the company (but is not active at all in the business). I get paid a W2 salary for my work I put into it and any profits are distributed to my Wife and I as “dividends”. However the dividends are still taxed as active income at the higher tax rates.

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.