I think the impulse to buy something satisfies certain needs, like honoring and strengthening our commitments, or broadcasting them to others. I think that as other fixtures of meaning and purpose (religion, patriotism, loyalty to our tribe) have lost appeal for many people in the West, consumerism has simply filled the vacuum. As you point out, buying things often fails to fulfill its stated goal (teaching us a language, getting us in shape, etc.). But, what it does do is give us some instant “ceremony.” I would add to what you’ve said, that in addition to questioning buying things as an effective way of reaching our goals, we also have to get good at creating alternate but still satisfying ceremonies.