My dad's family used to have a dairy farm. There was one point in time, like 100 years ago, where they rivalled Wiseman's for distribution in Scotland. However my uncle took it over in the late 70s and gradually made bad decisions with regards to running it. I think it was ok for a while because the long standing managers were on top of everything but when they retired everything became more chaotic. My poor uncle probably should have gone into academia as opposed to business since he's neurodivergent* and not particularly practically minded but his brothers had left to start careers in other professions, so I think he felt the mantle had fallen to him.

From what I can tell it was kind of inertia that completely killed the business. With supermarkets charging less and less for milk, the old way of operating a dairy farm as a regular business is not really viable. Successful farmers these days don't just do produce; they do open days and sell "country experiences" to punters who crave some kind of rural nostalgia. You pretty much have to be half farm and half events agency providing organised fun to school/office groups or families.

*From what I understand, they didn't really have the vocabulary to recognise this in the 70s. Family thought he was bright but eccentric.