A 5090 gets you 32GB with 1.8 TB/s of memory bandwidth for ~$4k, RTX A6000 gets you 48GB at 768 GB/s for ~$3.5k, 2x 3090 gets you 48GB for $2000 or so, and if you're willing to go into the wilderness, there are much cheaper options like the AMD MI50.

I'd also like to call out that "high bandwidth memory" (HBM) is a specifically defined thing[0], and is used in high end GPUs, and notably not used in Apple's machines.

I know you probably weren't referring to this type of memory in your post, but IMO it might be worth avoiding this term in the future unless you're referring to HBM, the standard.

[0] https://en.wikipedia.org/wiki/High_Bandwidth_Memory

Yeah this is just not the case at all; a 5090 or any of the recent nvidia workstation cards all fit this criteria.

Also, while memory bandwidth is important, it isn’t the only consideration. Apple’s architecture has memory bandwidth equal to a mid-range consumer GPU, but its GPU speed is much, much worse than, say, a 5080 or 5090. This translates into e.g. much slower time to first token on Mac systems compared to dedicated GPUs.