I would add one needs needs the right frame of mind for this. Maybe the hoarder is afraid of what would happen if the belongings were kept away. Would they feel empty?insecure?angry?
Often the hoarder will not want to change the rut they are in but pour out it with negative thought. Rather than become individuals who have no control a strange way they are in control of their clutter.Based on my observations of hoarders in some strange, way they feel power by having these belongings. Take my dad- constantly criticising others and picking faults- a sign of an insecurity. Despite myself being a lecturer, being forced to allow my unemployed brother to stay with me, paying bills, sorting the paperwork for my house and my dads- my dad chooses to pick on my U grade at A level in one subject all those years ago. In his eyes he only sees the weaknesess and hardly the strengths. Never mind I have been seriously ill to get this far, I have worked so hard in life it has almost killed me. I am told I am ungrateful if my dad finds an outdated textbook. If we dare to say anything he accuses of being critical but its ok to be critical in the patriarchal culture of my dad. I have had be hardfaced with my dad and not bat a lid at his hoarding and hostile behaviour.
Other traits I have noticed in horaders is not taking responsibility, not trusting others, paranoid and suffering from BSE epidemic (Blame somebody else).
Recently my dad has starting getting almost new furniture and placing it in whatever random place he can find resulting in mismatched furniture and looking like something that has been put together from the remains of a car boot sale. Ultimately looking cheap and unclean.