That's because of advertising. They wouldn't buy things they don't need if they weren't being manipulated to do so.
As you correctly observe, the statement "people wouldn't buy what they need without advertising" is obviously wrong. What I was getting at was manufactured demand, and my belief that it's a significant part of non-immediate-need purchases.
I don't have any disagreement with the claim that some demand is advertising-generated (in fact, it's a non-trivial part of advertising's purpose). Thanks for clarifying!
https://www.britannica.com/topic/conspicuous-consumption#ref...