Investing money is one of the easiest ways to build passive income. You can invest in real estate, stocks, mutual funds, ETFs, cryptocurrencies, etc. to generate passive income. In order to invest, you need money. If you do not have money, the only option left is to get a loan or sell your assets. Do you think it is safe to get a loan to build passive income? For instance, do you think it is safe to get a loan and then use the loan money to invest in properties, stocks, ETFs, Mutual funds, etc? You can use your passive income to pay your loan and after some time when you have cleared your loan, what ever you generate will be completely yours. Would you do this?