Being an adult is having a cupbaord full of cups that you never use a house full of everything you never use but don't want to get rid of! My Dad used to say anything in the shed/garage will come in handy once every 7 yearsy
I try and prune, but even so, there is a lot of stuff like bits of pipe, or brackets etc which "might come in handy". My dad is an appallng hoarder, basically at the mental problems level rather than mere eccentricity. I've seen him have a near melt-down when trying to throw away an old sainsburies receipt. On another occasion we had a row over me trying to throw away a bag of rotten veg that had turned into liquid slime, so it is beyond all reason. In mitigation if you chuck stuff away on the sly he may mention it but makes little fuss so it is now managable.
Previous triumphs included a broken fridge freezer left in the hall and very much in the way used as a cupboard. At one point I lived there, briefly whilst he lived elsewhere with his partner. Whilst it wasn't my house i had to make an executive decision and cleared out to the dump 11 estate car loads full to the roof. He made only a token fuss, as I guess he recognises it's a problem.