One popular method of making money is to look for undervalued assets, purchase and hold them and wait patiently for the market to recognize its value - at which point, you turn around and sell for a tidy profit. But those months and years of waiting implies that your money is tied up in that asset completely and you get no use out it.
For this reason, many successful investors embrace the notion of "return of capital" - which means, getting your capital back - and successful investors recover their initial investment as quickly as possible. This allows them to use that money for other promising investments and maintain a high-growth and diversified portfolio ("velocity of money").
To be able to recover your initial investment, one of the best and most reliable techniques is to find a way to generate income from the investment. For example, in the real-estate market, you might want to rent the parcel of land you have invested in, or rent the building/apartment that has been purchased. In the world of stocks, dividends provide a return of capital or writing calls could be a source of income; and for bonds, the interest payment does the same. It is a much harder story in the world of collectibles and similar investments, unless a museum is willing to pay rent to display your piece.
Whichever way you slice it, the ability find a way to generate an income from your invested asset will help you recover your invested capital quickly, and provide an additional margin of safety for your investment. This sharp focus on income is a key attribute of successful wealth builders, and remains the less talked about wealth building secret in their arsenal.