Several considerations to what other commenters have already said: * Rental properties, vending machines, etc have poor liquidity. What if you need to get your

Several considerations to what other commenters have already said: * Rental properties, vending machines, etc have poor liquidity. What if you need to get your cash back out in an emergency? This poor liquidity is particularly correlated to poor economic conditions (ie. it takes longer to sell a condo in a bad economy which is also when you might really need cash). * Many non-traditional investments are not actually passive. Even with a property manager, you still have to manage that person. Also, many investments can have quarters with negative cashflow. What might happen to your cashflows in a given period if a tree falls on your rental property breaking the roof and the tenants move out as a result? What if your property manager also quits on you because that situation isn't worth dealing with? * There are a variety of ETFs focused on non-debt income (Eg. high dividend equity funds). Vanguard's trades under the ticker VYM. If you come from a background purchasing equities, these kinds of investments might be more comfortable for you.