@Code For Broke
Just for the record, as I've only just seen this article and your comment.
This might be a good place to start if you don't get it:
https://excalibur.ac.uk/wp-content/uploads/2021/07/UKRI-Supercomputing-Science-Case.pdf
It's a few years old and very much a UK perspective, albeit with world-leadership in much of the science.
The demand for these supercomputing facilities is enormous and the results themselves often form the basis of research studies for hundreds of thousands of PhD-level scientists and engineers, complementing laboratory experiments and observational studies. The scope of applications is vast and the scientific returns may take decades, but never have any doubt about the long-term value. It's worth remembering Michael Faraday quoting Benjamin Franklin: "What use is a new born baby?" (Of course, some babies may turn-out to be more useful than some others).