In my own case, having 6 children in many different activities and commitments, more people need to be in more places than my wife and I can accommodate. Often we need another family car or two so that we can press our coming-of-age teen drivers into service for themselves or their siblings.
On one occasion after one of the family cars gave out, I had no transportation whatsoever. I needed a car.
On a different occasion when all my car needs were being satisfied, I purchased a VW Beetle for fun. I was able to save my money in advance and make my buying decision without any pressure. (After I accidentally flipped it over, I ended up cutting the top off, welding a roll cage into it, and making it a dune buggy that I would tow to the river bottoms).