Have anyone here heard of "hoarding"? It's a mental health condition where you collect so much of a particular item that it becomes a fire escape risk. It could be lots of books, lots of boxes, lots dolls/bears, lots of empty bottles etc. The collector keeps all of them because they have a sentimental value and they find it hard to let go of even 1 book / box / doll etc. The collection simply gets bigger, to the point that some of the items are over-spilling into their garden. It's a vicious cycle to break out of, similar to addictions.
So it looks like none of you here have reached that point yet!
I do need to declutter a little bit myself. I live in a 5m x 4m 1 up / 1 down house but with a relatively large garden, so I'm getting a shed built outside with shelves. Each shelf can be used for a different type of clutter, categorise it all then figure out which is sellable, which to give to a charity shop and which to throw away or recycle.
I recommend watching this episode of Obsessive Compulsive Hoarders (where available) it's fantastic and fantastical!
He is intelligent, articulate, his neighbours took him to court over his hoarding causing a health hazard, he represented himself and won
The best line in the show was when he said "I don't have a hoarding problem, I just have a lack of storage problem"