This interview article with James Kakalios on his book "The Amazing Story of Quantum Mechanics" has just enough details to pacify such a question on what QM is good for.
I present in the introduction what I call a "workingman's view" of quantum mechanics and show how if you accept on faith three weird ideas—that light is a photon; that matter has a wavelength nature associated with its motion; and that everything, light and matter, has an intrinsic angular momentum or spin that can only have discrete values—it turns out that you can then see how lasers work. You can see how a transistor works or your computer hard drive or magnetic resonance imaging—a host of technologies that we take for granted that pretty much define our life.
There were computers before the transistor; they used vacuum tubes as logic elements. To make a more powerful computer meant that you had to have more vacuum tubes. They were big, they generated a lot of heat, they were fragile. You had to make the room and the computer very large. And so if you used vacuum tubes, only the government and a few large corporations would have the most powerful computers. You wouldn't have millions of them across the country. There would be no reason to hook them all together into an Internet, and there would be no World Wide Web.
The beautiful aspect to this is the scientists who developed this were not trying to make a cell phone; they were not trying to invent a CD player. If you went to Schrödinger in 1926 and said, "Nice equation, Erwin. What's it good for?" He's not going to say, "Well, if you want to store music in a compact digital format..."
But without the curiosity-driven understanding of how atoms behave, how they interact with each other, and how they interact with light, the world we live in would be profoundly different.
I've always believed that as a physicist, you need to have a set of "here's what this was used for" examples on your back pocket at all times. When someone asked you "what is so-and-so good for?", you should be able to whip out immediately the direct application to such a thing.
Now, granted, some areas of physics will be more difficult for us to do that than others. However, you should always have a read-made answer, and the way Kakalios tackled in the above example of QM is the way it should be dealt with.