Is a business management degree worth it?

It's no better or worse than any other degree. I don't really buy into this concept of "STEM superiority" sometimes implied or outright espoused by people on here and elsewhere though, having studied a STEM degree and now studying non-STEM subjects. Those subjects aren't inherently better, harder, more interesting, more relevant or important for "society", or more "respectable" for graduate employers than any other traditionally academic degree.

However in my person opinion I think business type degrees are a bit pointless because you could just as well study a degree in some subject of particular interest otherwise and still be able to go into the same possible jobs. So if you had a deep interest in marine biology, history of art, anthropology, etc, but still want to work in "business" generally, you still can do so with a degree i those subject areas, and then you will have 3-4 very intellectually stimulating years at uni exploring some academic field that is of interest to you before going into the workforce.

So I would suggest pursuing a degree in something you have some particular interest in, even if you don't have any plans to continue with it professionally, personally. Of course bear in mind also the above is still largely pertaining to traditionally academic degree subjects. Note though that even this distinction is a bit arbitrary though, as arguably law and engineering (and business/management themselves) are "vocational" degrees, but they are also traditionally academic courses.

More applied or vocational courses may not always be perceived equally (whether fairly or not), so a degree in say, horticulture, might not be perceived as well as one in say, plant sciences (despite the relationships between the two areas and potential overlaps). Bear in mind also more vocational courses are usually designed to prepare you for, as the name suggests, a particular vocation, so they may not develop such a range of transferable skills as they are more focused on developing specific skills for a particular sector/role.

I thought a business management degree is designed to open many doors for you in terms of careers, hence you leave the degree with having developed copious transferable skills. I've heard that from a lot of people but I don't know how accurate their premise is. To be honest, I'm really not interested in studying my A-level subjects any further ( chemistry, biology and english literature). I'm also not really interested in a combination of those subjects and I have been interested in Business since year 11. I also agree with the stem superiority concept and only think narcissist believe in such a notion. In all honestly most careers, with the exception of some scientific and mathematical ones, don't really require a particular degree.