Solid state drives are very fast. Most programs can fit in cache for fast execution. Is there still a need for large amounts of RAM? Website are about the only thing that still rely on it.
the fastest solid state drive is some intel SSD running in PCIE 4x port is about 1.2gb/ second
yet this is very expensive
you can't compare with DD3 mem speed which on any computer today is about 15-30gb sec