This is called "compulsive hoarding", and most mental health professionals (arguably) see it as a sub-category of obsessive-compulsive disorder or OCD. If left untended, it can get quite extreme, with more and more of your life constricted and disabled by it. There is a biochemical and neurological aspect to this condition, and usually people are genetically predisposed to it.
Some people have so much accumulation, they will only have a narrow path from room to room, because canyons have been created by floor-to-ceiling stacks of newspapers and magazines. Stovetops, sofas and tables are buried. Fire and health hazards are created. And of course, your social life is constricted too - you’re too ashamed to have people over the house. So are your kids.
It also can be disabling to your checkbook, because another feature is feeling that you have to buy things - often useless things - because you might need them later. There are instances of people buying clothing 3 sizes too small because they might eventually lose the weight. Amazingly together-looking people sometimes have homes nobody ever sees, because they are so chaotically and dysfunctionally filled with stuff. (I’m sure on some philosophical/sociological meta-level, this is a reflection of our excessively materialistic culture run amok, don’t you think?)
There is treatment for this. What works is a combination of medication (usually SSRI’s) and Cognitive Behavioral Therapy, but only if you stick to the regimen. It’s very hard at first, because of the tremendous anxiety not hoarding generates. But, as with all OCD, it’s much harder to live with the disorder than to put up with the anxiety. And as you stick with it, the anxiety decreases.. With a skilled therapist-coach and the right treatment program, you can beat this.
So find a local hospital or clinic that has a tried and true OCD program, steel yourself and sign on. Check out Help with Obsessive Compulsive Disorder, Relaxation & Wellness and Help with Panic Attacks; these should support you when the anxiety gets rough.