Perhaps, the landscape has improved a lot in the last couple of years, there are lots of implementation tricks to improve efficiency on consumer hardware, particularly for inference.

Although it is clear that the computing capacity of the GPU would be very underutilized with the SSD as the bottleneck. Even using RAM instead of VRAM is pretty impractical. It might be a bit better for chips like Apple's where the CPU, RAM and GPU are all tightly connected on the same SoC, and the main RAM is used as the VRAM.

Would that performance be still worth more than the electricity cost? Would the earnings be high enough for a wide population to be motivated to go through the hassle of setting up their machine to serve requests?