Say it's 100-200 years from now and you're a 25 year old person. Anything you want is extremely cheap or free, there are automated factories that make things using something like 3D printers. You want a PS11? You ask your personal internet assistant for a PS11 and it's delivered to you by drone and it costs you pennies if anything at all.
One way to make money is to design something people want, you advertise your product on the internet and people order it and it's shipped to them. For example a doorknob that looks like a starfish. Manufacturing things to sell cost you very little money to free depending on what it is.
What would you design? What would people who have everything want?