Good god! Why on earth you need 32 core quad GPU workstation?
Same with GPU systems like redshift, alternatively I can dedicate half the machine to rendering and the other half to continued work.
I know
Unless you’re using Houdini, I think you’ll get the same result using Redshift with 16 threads. Houdini is the only DCC that uses more than one thread to prep the scen
Cycles is easily 5+ minutes a frame, maybe 20+ minutes on a threadripper if you have an interior scene or something hard to light. Even with Cycle's denoiser, you need a lot of rays to get a decent animation.
Even a short 10-second animation through Cycles will take multiple days to render on a Threadripper.
It can take a very long time just to process a 5 minute video.
Note that most price comparisons show that the iMac Pro is actually quite the deal.
Do remember that this 32-core Threadripper offers quad-channel memory, 64x PCIe lanes, and ECC support (!!). So the Threadripper offers pretty much everything a professional wants.
The only downside to Threadripper is that its multi-threaded performance is similar to a quad-socket / quad-CPU design (~200ns to ~300ns latencies to memory, depending on how many "hops" and NUMA nodes and stuff...). So audio professionals and gamers who are IIRC latency bound may want to stick to Intel.
But almost everyone else is bandwidth bound (video editing, 3d rendering, compilers, web servers, LT Spice...). So most professionals would probably prefer a Threadripper.
It's the case that building a comparable computer (in terms of the specific iMac Pro hardware) is very similarly priced BUT requires labor, the purchase of an OS and additional peripherals: https://youtu.be/SONKIJd8xRM?t=187
That said, your point that Apple could've chosen better hardware at its price, is reasonable but off topic.
[update]Sorry he said $20,000. SO you are right