That seems like a really bad way to spend money. Why limit a person to a single workstation if the workstation is the limiting factor? This is where we get clouds or if it must be done locally, rack mounted systems with many cards.

If you are doing it solo, with "just the hardware you happen to have", it matters a bit less. If you are doing it constantly to make money, and you need a lot of power, buying a one-person desk-machine makes no sense.