This is, of course, a massive question in Sociology. We need to consider whether marketers actually persuade us that we need items that we don't actually need or whether they are responsive to our needs and desires. When I teach this subject in Sociology, I always find it useful to look at the issue of fashion. Why do we wear what we wear? Who defines the look that we go for? Many students have never thought about why we wear specifically the clothes that we wear.
However, if we think about it, the fact that we wear modern clothes rather than doublet and hose or formal wear all the time is because of the nebulous concept of fashion. Fashion is something that is not decided by us but is decided by clothes designers who work out what is going to be "in" and what will be "out" next season and plan the market accordingly. What we wear is therefore not so much a result of what we want to wear but the way that we follow trends that have been decided for others.
Of course, this isn't necessarily true for all products. There are products where the interest is customer led rather than market driven, but we need to be aware of the complex interplay between our desires and how they are manipulated and affected by marketers and advertising, often without us even being aware of it.