The casual market is actually lots of different tastes served by different games. The industry attempts to brand it as one big thing to be ignored/ridiculed/squeezed dry, but any real business understanding would see that there are casual niches to fill much like JRPGs and FPSs can be made for different core audiences.
And yes the same people who play core games at home in their free time can play casual games on the bus or between classes. The terms core and casual are misleading in that they imply people are one or the other.
Even the same game can be played in a casual or core way. You can just hop on CoD for a match with your friends. Or you can be a professional CoD player and travel to tournaments. Is CoD a core or casual game? Neither.
