I rarely buy something I don't need, but "need" is highly subjective and in comparison to the next best alternative. A lot of people buy what seems to others to be useless crap because the alternative is to have your money's value eroded by inflation. Once I learned that I can buy a better form of money, the next best alternative changed. Same thing for when I learned to invest in stocks. If stocks are overpriced I might go for some bitcoin. If bitcoin is hitting all time highs, I might buy stocks that month. The more alternatives you know how to use to your benefit the more resilient you'll be.

Also, sometimes I buy things I might not want to hold because they're capital goods. I need two cars so that my wife and I can get to work. We could get by with one or even zero, but we concluded that two cars is a good investment because it saves us a bunch of time that we can use to gain more utility than we lost from buying the cars.