There are working quantum computers that are not only feasible, but exist, can be rented on the cloud, and are people pay money to use.

Whether these are a commercial success at this point in time is missing the forest for the trees. A LOT of money has been put into getting as far as we have, and the limited market for using these machines at the moment means that getting a return on investment right now is difficult. But this is/has been true of every new technology.

And quantum computers are getting better & more energy efficient year-by-year.