in the case of shopping (aka "retail therapy") to cure the dysphoria blues, I don't really think it's about materialism so much, but more about simply getting out and taking your mind off your personal problems for a while. Also, getting dressed up and going out shopping for pretty clothes or shoes or jewelry is somehow identity-affirming in itelf. When I feel bad and go shopping it does cheer me up, sometimes significantly, even if I only end up with a new pair of earrings or whatever or nothing at all.