I understand where you're coming from, but I think you're misunderstanding why many people buy the things they do.
Most consumer purchases outside of food, rent and utilities aren't sacrifices made to made to optimally meet a physical need but instead a fun activity that the consumer engages in order to make them feel special/important.
You can see this in economic terms if you go to buy a second-hand appliance, for example. A current-model washing machine that costs $800 in store might cost $300 on Gumtree or Facebook.
Even accounting for the depreciation (which might be $50 on a year-old machine), less than half of the perceived value is actually in the washing machine itself. The rest comes from the luxury experience of purchasing a new appliance - looking up reviews online, comparing prices, convincing yourself that this particular model is optimal, going down to the nice store to get it, haggling the guy down and finally unwrapping your shiny new thing.
It may not be an optimal distribution of resources in terms of achieving mankind's greater goals, but most retailers are a luxury service just like wedding photography, fine dining or high-class escort services.
We exist to meet a demand.