How large (or small) is the audiophile market?

I don't know the answer, but the above AI response is probably faulty.   It basically says high end or premium audio accounts for half of all audio equipment sales.  I suspect their definition of audiophile, high end and premium would differ from that of most participants in this forum.

for speakers, about 1.5-2 billion a year. The AI answer is confusing and wrong. 

Very vague guess: if the average spending on speakers is around $1500 then it's a million people a year. Given that a 100 million cars are sold a year, it sounds reasonable. It's a small market but far from dead.

Shrinking every year.