This kind of fundamental research though is absolutely worth it. For a fairly small amount of money (on the nation-state scale) you can literally change the world order. Same deal with fusion or other long-term research programs.

Quantum computers are still in a hype bubble right now, but having a "real" functional one (nothing right now is close IMO) is a big a shift as nuclear energy or the transistor.

Even if we don't get a direct result, ancillary research products can still be useful, as you mentioned with fusion.

People who believe in quantum can put their own money where their mouth is. Plenty of quantum stocks to speculate on out there.

You are right about that (well, except all the progress in classical complexity theory and algorithms, cosmology, condensed matter physics, material science, and sensing, which stemmed from this domain).

But, for the little it is worth, it took much longer between Babbage conceiving of a classical computer and humanity developing the technology to make classical computers reliable. Babbage died before it was possible to build the classical computers he invented.

If you are going to use Babbage as the start of the clock, we must use the mechanical and electromechanical logarithmic and analytical engines created in the late 1800s/early 1900s as the stop.

We must also use 1980 as the year in which quantum computing was "invented".

As far as progress goes, in all of those fields there are naught but papers that say "quantum computing would be totally rad in these fields" or simulations that are slower than classical computers. (by, like, a lot)

There has been a programmable electromechanical computer build in the late 1800? Not just a simple calculator? Please share examples, this sounds awesome.

Yes, late 1980s is when I would say quantum computing was conceived.

I gave plenty of examples of positive outcomes thanks to quantum information science in my parenthetical. It is much more than the overhyped VC-funded vapor.