We make regular purchases every day, and most of the time, I believe people buy products because they need them. On the other hand, it is also true that sometimes our purchases are of human desires or so-called "wants", but this does not necessarily mean that we want these goods only because other people have them. It’s very possible for humans to like something purely because it is good to have them. Therefore, in my opinion, whether people buy products because they really need them or other people have them should be discussed case-by-case.
For goods like groceries, we buy them because they are essential for our everyday living. Using my mother as an example, each Friday after work, she would go to the grocery store to do grocery shopping for the family. Although she gets very tired after a week of work, she still does the shopping. She knows the importance of food for a family. Whether for breakfast, lunch, or dinner, she always prepares us a healthy and delicious meal. Giving us food is a way for her to show her love and care. She is not the only mom who does this. Most moms would go to grocery store to pick up food for the family. It is not because other moms buy food for their family so they need to do it as well, but rather, as humans we depend on food for survival. For college students, same principle applies. It is easy for students to get overwhelmed by school work and social life, but when it comes to grocery shopping, students still make time to do their shopping list. Buying healthy and nutritious food is necessary for students’ life. In this case, we buy products because we need them not because others have it.
For some luxurious goods, however, such as an expensive bag or a pair of shoes, people might purchase them because others have them as well. This phenomenon is especially common among high school female students. As girls begin to care more and more about their looks, their perspective on beauty starts to change collectively. For example, a girl who wears a pair of UGG shoes may eventually starts a trend. If her classmates think having a pair of UGG is cool and pretty, then they will want a pair too. So it is common to see within a school that girls dress very similarly with one another. This is an example when purchases are not needs, but simply because others have it and so one wants to have it too. According to a survey conducted by Trend website, a significant percentage of luxurious goods buyers consider luxurious brand as a label for their social status or wealth and they tend to choose the brand that their colleagues or friends recognize or value.
In sum, I think most of the time people make purchases because we need them, but there are rare situations where making a purchase is because others have it.