Historically, this is the norm. The British Navy in WWI was a behemoth, but still couldn't force safe passage through the mines and cannons of the Dardanelles Strait against what was considered a third-rate power. "A ship's a fool to fight a fort."
It's worth remembering that "fusion = abundant power" is a guess about technology that hasn't been finished yet. Fusion power might turn out like solar panels (easier to build than expected) or like nuclear fission reactors (harder to build than expected).
A Fire Upon The Deep is a fantastic novel for programmers to read, and I think the prequel A Deepness In The Sky is even better. There are some amazing old-school coding jokes in there, like that everyone thinks the universal time counter started at the first moon landing, but programmer archaeologists know it was really 15 megaseconds later.
People always need to be reminded, though. It seems to be in human nature to fear bad publicity, and the people who fear it less end up with disproportionate power as a result.
"Little by little, over-inflated results and breathless breakthroughs betray trust. They throwing dimes in a wishing well which people rapidly start to expect will never pay compound interest."
"Then, when one of those people is elected to parliament, or Congress, and start to cut the budget for the National Science Foundation, or declares that All Research Should Be In The National Interest (whatever that is), I wonder how much we reap what we have sown."
The climate shock from stopping aerosols would be a crisis for the planet, but we would have more than weeks to stop it. First it would take months for the aerosols to leave the upper atmosphere, and then years for the earth to heat up to its new equilibrium temperature - catastrophe, but not likely the end of all life.
I gave my engineering students a CO2 removal design problem once, and at the end, asked why the theoretical efficiency had increased in the time since the textbook was written. The answer was that the concentration of CO2 in the atmosphere was higher.
It is tough to beat classical computers. They work really well, and a huge amount of time (including some of mine) has gone into developing fast algorithms for them to do things they're not naturally fast at, such as quantum chemistry.
Yes, in fact they might be useful for chemistry simulation long before they are useful for cryptography. Simulations of quantum systems inherently scale better on quantum hardware.
I think that's what was meant by "Middle Ages/ early Renaissance" in the comment above. In this time period, literacy was a rare advantage. For instance, in early modern England, literate people were not subject to ordinary criminal courts on a first offense.