You've been able to buy a quantum computer for years, so trough of disillusionment.
although DARPA has them, so probably making our way through the trough of disillusionment.
DARPA feasibility studies:
https://www.theregister.com/2024/06/24/darpa_quantum_computer_benchmarking_papers/
available quantum computers:
https://quantumzeitgeist.com/how-to-buy-a-quantum-computer/
You're not going to hear a lot about them the same way people didn't hear about personal computers back in the '60s,, but there are and have been many companies consistently working on improving the accuracy and power of quantum computers.
regular computers were around for decades before being successfully developed into personal machines with commercial utility, quantum computers are kind of in that zone roght mow, big room sized things that have a couple cubits.
but they are real and available, and the field is constantly in development