You can spend half of the specified costs on every single one of the listed components with zero impact on your ML work productivity. $330 for 64gb of ram, really?
That is high end RAM binned at 3200Mhz. Consumer RAM is mostly 2133/2400 and with servers often using 2666. RAM at 3200 (PC4-25600) gives you about 25% more peak bandwidth than RAM at 2400 (PC4-19200) and about 16% more than 2666 (PC4-21333)
That might be true, but you don't usually care about that for ML workloads running on GPU. Bottlenecks are typically elsewhere.
Not true, 3200 CL16 can be nearly as cheap as slower RAM nowadays, with multiple brands at sub-$60 per 16GB stick[1]. OP is paying extra for RGB, as another commenter points out.