Passive income is an important strategy which the millionaires actively utilize to increase their wealth. With passive income, you make money with every passing tick of the clock, whether you’re asleep or you’re awake. It will keep money flowing when you lose a job or experience any financial difficulty. When you’re concerned that you can save enough of your earnings to achieve your retirement goals, building wealth through passive income is a tactic that might appeal to you too. The answer to this question is simple; time and money. Time is man’s most important commodity.