At the extreme end of the clutter spectrum are folks who suffer from what some call disposophobia—fear of disposing. In other words, they hoard. According to one report, nearly a million junkaholics suffer from this psychological, and the proof is in the piles. To help those who suffer from disposophobia, a national support group called Clutterers Anonymous models itself after the twelve-step format of Alcoholics Anonymous.
Source: wiktionary
Compulsive hoarding (or pathological hoarding or disposophobia) is the selfish acquisition of possessions (and failure to use or discard them)...
Source: wiktionary
The fear of throwing things away. Disposophobia, I remembered. A disease immortalized by the legendary Collyer brothers, who'd been found dead in their mess in a Harlem brownstone.
Source: wiktionary
Compulsive hoarding has also been labeled "disposophoia" because the person with this disorder feels a real and palpable fear of throwing or giving away, even if the items are essentially worthless.
Source: wiktionary