Do you believe that the ninth symphony syndrome (NSS) is real?

Is it true or coincidence that some of the greatest composers of the Classical and Romantic era's such as Beethoven, Schubert, Dvorak, Mahler, as well as others, died after writing only nine symphonies and never finished their tenth?

Of course it is just coincidence. But it is a strange coincidence. Since Beethoven, many composers have not succeeded in writing more than 9 symphonies, among them

Malcolm Arnold
Anton Bruckner
Anton铆n Dvo艡谩k
Gustav Mahler
Franz Schubert (although a mistake in the numbering of his symphonies lists a non-existant (or, at best, spurious) 7th Symphony so there should only be 8 in the list)
Eduard Tubin
Ralph Vaughan Williams

Mahler got around the Ninth Symphony 'curse' by calling his Ninth Symphony 'Das Lied von der Erde' (The song of the earth) and not calling it 'No 9' but then died before properly completing his numbered 10th Symphony (!)

Having said all of this, many composers easily exceeded nine symphonies and so I suppose the simple law of averages will mean that some only reach a certain number.

no

I don't know if that's real, but I don't doubt that talent such as that can wear a person out quickly. I wouldn't be surprised if it was just a case of the non-stop work that actually caused their deaths instead of a supposed syndrome. That'd kill anyone, regardless of what they did for a living.

I've personally never heard of NSS. But that is pretty strange.