The popularity of products, activities, behaviors and opinions depends not only in the intrinsic value itself but also on the extrinsic value that individuals and groups place on it. We can start thinking about why a fashion accesory, social-networking site, or a political stance rises in popularity among certain groups and then is dropped, but it´s necessary to understand why multiple factors contribute to the utility of adopting the object.
Consumption decisions signal people´s identity, are affected by people´s place in a social network, and both influence and are influenced by other network member´s opinions and consumption decisions.
Although the human identity is difficult to reveal,consumption is desirable generally in situations where a person wishes to signal differing identities to differing groups (as when, for example, criminals want to identify themselves to other criminals but not to society at large). By contrast, groups that want to flaunt outsider status (e.g., punk rockers) will adopt conspicuous behaviors or attire (e.g., a mohawk haircut) that they know will deter imitators.
That is the reason why the adoption of social norms or political positions are a form of consumption. Hence, the people adhere to costly social norms in order to differentiate themselves from other people.