It's not just that the CPU is cheaper than the GPU. They also claim it's faster than the more expensive GPU. Meaning if you rent a box in the cloud for training

It's not just that the CPU is cheaper than the GPU. They also claim it's faster than the more expensive GPU. Meaning if you rent a box in the cloud for training it'll cost you less since you'll rent it for less time, and if you buy the hardware you can train more models and thus need less hardware to train as much as with GPUs before. So if it's 3.5 times faster then you require only roughly 30% of the time (or hardware) it took before, both savings combined seem pretty significant to me. Edit: quick napkin math, let's take your $7k figure for the GPU and 4115 for the CPU. We need one third of that CPU so 4115 * 0.3 = 1234.5 now 1234.5 / 7000 = approx. 0.176. 18% of what it cost before...