At least where I'm from, new HPC clusters aren't really asked for by the users, but they are "infrastructure projects" of their own.
With the difficulty of spending taxpayer money, I fully agree. I even think HPC clusters are a bit of a symptom of this. It's often really hard to buy a beefy enough workstation of your own that would fit the bill, or to just buy time from cloud services. Instead you have to faff with a HPC cluster and its bureaucracy, because it doesn't mean extra spending. And especially not doing a tender, which is the epitome of the inefficiency caused by the paranoia of wasted spending.
I've worked for large businesses, and it's a lot easier to spend in those for all sorts of useless stuff, at least when the times are good. When the times get bad, the (pointless) bureaucracy and red tape gets easily worse than in gov organizations.