Patriotism and Celebration

In general, I think that patriotism is at best unnecessary and at worst entirely immoral.  How, then, did such a bad idea become so popular?  There are many reasons, but in American culture one of the most appealing may be the frequent institutionalised celebration of patriotism.  The Fourth of July, for example, is an occasion which appeals to many people.  It provides an opportunity to unite and celebrate a shared cause.  It is also fun for children, due to all the excitement and proliferation of high spirits.  Merry parades, music, and pleasant food are all strong motivations for most people.  While this sort of tradition obviously did not spark the idea of patriotism, I think it likely provides a lot of fuel for the idea to continue, and to be as popular as it is.