The OP seems to imply that it is a kind of moral failing to not be curious about everything. Plokavian's answer is good for covering why many people simply do not have the time to be curious, but I think that their answer fails to cover two points: 1) people in academia who are, to a certain extent, paid to be curious; and 2) why should everyone need to be scientifically curious?
People in Academia
What do you think drives people to pursue graduate studies in the first place? There are many factors, but in my experience curiosity is one of the top factors.
In applied science I have met researchers who study the patterns that water drops form when they land on a surface. They openly admitted that they have no idea what application it could be used for, but they thought it was interesting so they spent some time investigating it. In other words: purely out of curiosity. Even in areas of research where the application is clear, a lot of research seems to start with the question "I wonder what would happen if...?". That is, curiosity. Why would they care how a computer works? They have other things that they find more interesting that they would rather spend their time on.
Why do people need to be scientifically curious?
The OP seems to define curiosity as a desire to understand how things work, such as technology or physical phenomena and seems to conflate curiosity with intellectual stimulation. But there are many ways to be intellectually stimulated without being curious about how everything works from a scientific perspective.
Consider engineering (my field). I know many students who left their undergrad to work in industry. Of course some of them only pursued the degree for a good stable job (nothing wrong with that!) but many others derived great satisfaction (dare I say, intellectual stimulation) from solving problems. To them, a computer is not necessarily something that needs to be understood down to its finest workings. Instead, a computer might be a tool in a big project that is working towards solving a problem for a client. It is the pursuit of the solution that drives them, not a need to understand how all of their tools work.
Consider a doctor trying to decide on the best treatment for a patient (often many patients). It is a complex problem that requires a significant amount of intellect. The doctor draws satisfaction from solving the problem and restoring health to their patients.
Consider an artist (not necessarily my forte!). They may want to explore new ways of expressing ideas or emotions. Exploration of any kind is fundamentally an act of curiosity. They may be curious about how people react to a piece of performance art. They may be trying to solve a problem of how to abstract concepts or objects to their simplest forms (see abstract art).
Finally, some people simply have other priorities in life. It is not a moral failing on their part! We need scientists and engineers and mathematicians and doctors and artists and many others who push forwards in their fields in the name of intellectual stimulation. But there is much more to society than that!