Why are people so attached to their possessions? Why do people "set great store" by their things? If for example photos are lost or damaged, why is this a big deal? It seems to me that relationships are the only really important thing, and because we never know if the person will come home from work alive, all we can do is deal with "the person standing in front of us at the time."
I think it's a primal need that is built in via natural selection. Those that had attachments to places and things outpased those who didn't. The affection a child shows for a favorite toy or a teenager shows for a favorite pair of shoes. Also, when a possession has been won over a great hardship, it has intrinsic meaning. This has a social and mental advantage when connecting to others. Social animals (like humans) must succeed in interactions to remain prosperous and leads to groupings of individuals for the overall benefits.