From watching the TV show, Hoarders, and several others on the topic ...
The only way a hoarder will change is if faced with a dire consequence that he/she really doesn't want, such as having children taken away, the house condemned, the family move out and leave the hoarder, etc. Even then, and even with the help of a professional organizer, it's likely to be only a partial cure.
This behavior is hard on the family, and then he's verbally abusive besides. My feeling is, give this man a dire consequence and the offer to work with an OCD therapist - maybe the family members together can stage an intervention and confront him with the effects on the family and the dire consequence.
My husband is a mini hoarder and I constantly tell him not to buy more stuff, but his excuses run from "it's cheaper by the multipack" to "I thought it would make a nice decoration." I am firmly putting my foot down and calling the disorder by its name, but I do it nicely and with gentle humor. Doesn't sound like that would work with your dad.
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A finger in every pie.