"Quantum technology, not unlike practical fusion power generation (something the government stuffed £20m into earlier this month), is one of those things that promises much, but has singularly failed to deliver. "
Huh? No. It has not. Progress is slow. But it is there. It does exactly what it says on the tin. It calculates probability distributions, mainly so you can "simulate" other quantum effects. Otherwise, it allows you to do some calculations quicker (travelling salesman) but with some probabilities distributed (some uncertainty in the result, unless you can figure out robust quantum circuits and results).
This means, say for example, a protein folding requirement to make a medicine, you can simulate and design a protein. Theoretically it should be quicker on a quantum computer than a standard one (providing we can set up the QM computer quicker than it takes the standard one to spit out a result, which is not a given just yet).
Yep, that result possibly won't be 100% accurate (quantum uncertainty, or probability distribution), but as it's a medicine design, you are still producing physical tests to narrow it down.
Alternatively, it could be used to crack encryption, with again, similar results. There are currently chips with a few dozen Q-bits, so giving a few more years, we could see 100s or 1000s of Q-bits, and finally hit a "useful" use case, beyond the current simple research.
Unlike Fusion, which has real physical limitations we may/may not overcome, Quantum Computers are a simple continual progress as we already saw from classic Microchips. It's just a matter of time with QM chips... slow, but sure!