Before spending $$$ on the hardware accelerators, there is still a lot to achieve using software optimizations for inference and trainings workloads. We optimized GPT-J, and others, for real. https://centml.ai/benchmarks/
These NVIDIA A40 GPUs mentioned on the page you’ve linked cost $4000 (Amazon) to $10000 (Dell), deliver similar performance to Intel A770 which cost $350. That’s 1 order of magnitude difference in cost efficiency.