What is useful / useless can be subjective, but remember big companies are trying to manipulate to get people addicted to their stuff be it sugary foods, internet gambling (inc. crypto), tech gadgets, alcohol or whatever.

If no one bought useless shit (again what is that?) and just got say long lasting furniture, decent food, shelter etc, you’d have a situation where everyone could live based on fewer hours of work most likely. What to do with the time? If bored then volunteer? Talk to your family and friends? Hobbies?

There is plenty of economy outside of useless shit. I don’t see how we can get around needing police/fire/hospitals/defence/research/science etc.

Lol. If nobody buys anything, why would you need money?