I'm a data scientist and regularly work with multiple datasets simulataneously that require the RAM usage. Both Python and R rely on in-memory processing. Loading on/off disk is substantially slower and does not fit with what I am trying to do. For really large datasets I also have a 28 core Xeon with 196GB that I can remote into, but it is nice to not have constraints on my laptop.
Of course, you could go with Hadoop or Spark to process some of these datasets, but that requires quite a bit of overhead and its easier (and cheaper) to just buy more RAM