It was an eye opener to watch selected episodes of Hoarder on TV. People would give up kids, health, life even to have the stuff. The show dealt with a variety of relatives and reactions from friends and neither had any affect on the hoarder. The professionals acknowledged the difficulty and took it slow with counseling along the way (expensive and not often available).
All I can say is pick your battles carefully. Unless there is counseling to go along with any medications, the person will not change. No "logic" in the world appears to work. It is a brain wiring issue.