What is investment income?
The world and the markets keep changing, but people's basic needs have stayed the same since we lived in caves. Clearly, if you want a secure income you can depend on, you want to invest your money, so it'll help supply people with those fundamentals: food and shelter. Water and fire.
People are always going to buy basic products. A recession, even a world financial crash, can certainly slow — but NOT stop — their sales. Obviously, seven and a half billion people around the world will want to fill their bellies and sleep under a roof at night. That's the safest bet going.