Mostly because I use this for development.

If a model takes twice as long to run.... I'll live. Worst-case, it will be mildly annoying.

If I can't run a model, that's a critical failure.

There's a huge step up CPU->GPU which I need, but 3060 versus 4090 isn't a big deal at all. Indeed, the 24GB versus 16GB is a bigger difference than the number of CUDA cores.

The thing about RAM speed (aka bandwidth) is that it becomes irrelevant if you run out and have to page out to slower tiers of storage.