Another option: A third of all cash held by US non-financial companies in 2015 was made by 5 US tech companies oversea

These companies might pay taxes to oversea countries when they extract their money to the US. So it might make sense keep it oversea.

Obviously

I work for a big software company and work on a huge product.

The number one productivity killer is Broken Code.
Broken builds, bugs which prevents the product from running, newly (undocumented) configuration.
Sometimes it takes me days until I can actually start developing.

Proper testing environment is a valuable asset for productivity.
Beyond the obvious reasons of making it easier to clean bugs, test by running is a time consuming method.
Our product is heavy and takes ages to start running and it surely consume my time when I'm developing.

That brings me to slow machines which is not a major time killer but is very easily fixed and I'm pretty sure has a good ROI.