I have an opinion about hoarding that has been formed by talking with my Mother about this very thing.
After the recent passing of my Father & my Mother having a stroke & going into care, I was left to clear out the house & dispose of possessions. So, so much stuff, just stuff that two hoarders had gathered over many years. So much with no or little value because that is how come it is there in the first place. A poverty mentality developed from being children of the depression & WW2 era as a basic training ground in thriftiness.
To the washing out & keeping endless amounts of margarine containers, yoghurt, ice cream, plastic bags, plastic cutlery, clothes, jars & bottles, in fact anything that even remotely looks like being able to repurpose. The thrift thing means that you keep your money & get something for nothing.
Thing is, no depression now & a time of prosperity & plenty, so new things keep coming & the saved stuff never gets used for what it was saved for. Problem.
The basic training mentality of thriftiness does not change & gets a modern title of "hoarder" because they collected stuff for the future when it may not be there. Just as it was not there in their past.

Something of value has an intrinsic value that was there all along, even if purchased as a bargain. It therefore has a sale price as it is not junk.
Whether this forms the basis of a collection, sometimes, if there are many, maybe.

My Mother has a collection of rocks that she picked up while walking the dog & in car parks & such. She collected them on the basis of them being so close to spherical that some you would think were machine made. Worthless rocks, but still a collection. The empty margarine containers are then a collection too, even though they are hoarded.

The idea that hoarders collect trash stuff & collectors collect things of value is flawed too.
It seems that a reasonably minded collector turns into a hoarder when the collection overtakes & goes crazy. The persons ability to keep order goes too & there is no room left to move about the collection of stuff. No one quite knows any more what is actually in or under the layers of mixed stuff.

I am transitioning from collector to hoarder & need to pull back.
It, however is intrinsic to my blood. Grin
O.M