I actually don't believe they are happy, I think that something like that has to be very rare, or impossible. It could be a masking tool someone is using, or it could indicate ignorance , or it could indicate malevolence.
Best case scenario, it is a case of ignorance, because something horrible is happening at this moment somewhere in the world, and the disconnected person is fortunate not to sense or perceive it. If it is a front, then the device is used to cope with some horrible problem they have. If it is malevolence, then the person sees or participates in bad things in the world, and does not care, allowing for their mirth. They either effectively suppress what they should feel, or they truly don't care in a sociopath type style.
This is why I think at best, people with a fully opened awareness come to trust in forces greater than themselves, that will make things ok. The logos, or fate, or god, or gods, or the scientific corpus. A very aware person seems to want to tap these for contentment, otherwise what are they hoping in?