Edit: simplified version of my assertion: current budgets are X. It would cost Y to harden infrastructure against an event 10 times as large as the Carrington event. Even if it were trivial to increase the budget from X to X+Y, it's probably not a good use of money to perform such extreme hardening. This is true for all positive finite values for X and Y in a world where we still have cancer, heart disease, poverty, etc.

If I read you correctly, you're making an argument regarding the marginal effort to increase the budget by Y.

My argument is about the millions of things we could do with Y that would be more beneficial to human flourishing. Even if it's trivial to increase the budget by Y, that doesn't imply that it's trivial to increase the budget by Y enough times to run out of more important things to do.

Q: Are governments prepared to handle a solar storm 10 times as big as the Carrington Event?

A: Probably not, and that's not something we should fault them for or worry about.

Original (longer) argument:

It's possible that hardening against a Carrington-level event is a good use of money, but that's not the original question. The original question is about an event 10 times as big, twice as big as the previously known largest event.

If I understand your assertion, you're asserting that the money could easily be raised with little downside. Maybe it can be. For the sake of argument, I'll grant you that.

But my assertion is that it's not a question of if the money could be raised to harden against a 15k-year solar storm. My assertion is that even if the money were already in hand, hardening against such an extreme event is probably not worth the cost.

Whatever the budget is, it will be finite. Given present technology, whatever that budget is, it won't be sufficient to give all people worldwide a utopian lifestyle while fully funding all promising medical research, etc. Tradeoffs will need to be made. Hardening against a 15k-year event an order of magnitude more powerful than the Carrington event is probably not the best use of finite budget.

If I could start a side gig in a polka band and sell plasma to raise enough money to make my Florida home polar bear proof, that wouldn't have any bearing on the wisdom of polar-bear-proofing a home in Florida. Even assume that cost were the only downside to polar-bear-proofing a home, the availability of the money wouldn't be the problem with the plan. The problem is that the other things I could do with my limited resources would be much more beneficial. Yes, all else being equal, a polar-bear-proof house in Florida is better than a non-bear-proof house in Florida. In the real world, all else is not equal.

There is almost always a trade-off. Some risks aren't worth mitigating, and we're better off accepting them than either worrying ourselves over them or wasting limited resources on unwise mitigations.

My point is that a lack of political will to come up with the funding isn't the biggest obstacle to such extreme measures.

Perfect safety is a bad goal, and worrying that we aren't perfectly safe is unwise.

Edit: if I've missed something and you're talking about some hypothetical world where we've already solved cancer, heart disease, poverty, wealth inequality, climate change, polio, dementia, put basements / tornado shelters in all of the houses and trailer parks in Tornado Alley, figured out why the laundry always contains an odd number of socks, etc. Sure, then if we could scrounge up enough money to harden against a solar storm 10 times as powerful as the Carrington event, then go for it.