You can wipe it away like that, but it is the entire point of Chinese leadership since a long time, even opposing parties, that what once was China will be China again. So the 'who cares' is the vital point in why they are doing this; they care very much, not about the pieces of land or the people, but just the simple fact that they consider it China because it was taken from them (and they always said they will get it back) no matter who say they own it now (Taiwan is not uniformly recognised as a state). And I believe many (majority?) on the mainland agree with this, even if they don't agree with the CCP.
You can wipe it away like that, but it is the entire point of Chinese leadership since a long time, even opposing parties, that what once was China will be China again. So the 'who cares' is the vital point in why they are doing this; they care very much, not about the pieces of land or the people, but just the simple fact that they consider it China because it was taken from them (and they always said they will get it back) no matter who say they own it now (Taiwan is not uniformly recognised as a state). And I believe many (majority?) on the mainland agree with this, even if they don't agree with the CCP.