"Generally available" means that I can order one or a dozen today for MSRP or less and get a shipping date between "today" and "end of the week".
"In demand" means that I can order one today for a little over MSRP or look around for a sale to get one under, but I might not be able to find a single supplier who wants to sell me a dozen at once.
"Speculation bubble" means that I can't find anyone to sell me one at MSRP without going to ridiculous lengths like setting bots out to scoop the competition, and I certainly can't call a distributor to get a dozen at MSRP -- but if I'm willing to pay a high premium, I can buy one today.
I think RPi4 is in a speculation bubble.
I'm sure the pricing doesn't bother enterprise or industrial users, and the Pi Foundation is almost entirely devoted to catering to them.
But hobbyists are super sensitive to pricing and ease of access, and the only reason to still use it is that tons of projects are already built to run on Pi's. Even then, Units are almost entirely allocated to enterprise/b2b demand, so the retail customer market is so extremely undersupplied that it's just not worth actively hunting for days just to run an interesting app you wanted to tinker with.
What is your definition of a dead market?