The costs are multiple. We organise society around the productivist maximisation of output, requiring us all to work at a dizzying pace despite the dramatic increase of productivity per hour of labour over time. We compensate for the modest time we have to ourselves, 'leisure', through a lifestyle of extreme consumption. One of the underlying reasons that we want to consume more, is as a marker that we are the kinds of people capable of high consumption. Having a nice house, clothes and car, going on nice holidays, validates our social status and esteem, or worse, feeds our pride and envy. We organise the whole of human life and society around production to satisfy our ape-brain psychology, to feed our bottomless status-seeking. It's a huge collective action problem, and we would all be better off if we jointly committed to working less, and shifted away from private consumption to public goods that can be shared in common.
There are also important questions about where spiralling levels of consumption run-up against natural resource and ecological limits, and the fact current rates of western consumption depend on cheap labour in the global south that won't last indefinitely - and in the case of China relies on a historically unprecedented reallocation of national income away from its citizens, and towards gargantuan capital investment at home and abroad.