It's less AMD not doing commercial GPGPU than nVidia completely staying out of the PC and server market. Remember AMD competes with both of them (nVidia and Intel) and is smaller than both.

AMDs revenue this quarter just passed Intels for the first time in history and they still are dominating in the HPC market which is fairly immune to the AI bubble (while also selling everything they can build at a high premium to AI datacenters).

AMDs margins on their Instinct datacenter GPUs is nearly as good as nVidia's. They just can't get contract volume at TSMC to make more because nVidia buys all of it.