Clutter and hoarding
There is a tendency nowadays to have more stuff than we have places to put stuff, and many people live in rather chaotic and unsatisfying environments in which every horizontal surface is covered. When clutter gets really out of control and the clutterer cannot let anything go, it becomes a troublesome disorder. Taken to extremes, this can ruin the lives of both the person who hoards and anyone who also has to put up with it. Hoarding can be dangerous because of fire risk, and in extreme cases, from avalanche! It is rare for people who hoard, who keep things because "they might come in use", to think they have a problem.