Yes and no. Spent money is rarely meaningless economically speaking. Most of it will get respent in the economy thereby increasing economic output of the society. You are right, though, that the money can be wasted in terms of what the public gets from the initial spending. It can get a bomb that will eventually be blown up in a foreign country (and hence of no utility to the domestic public) or it could get a hospital or school. Small point, but I think it is at least important to understand that economic production can be increased even if the public gets nothing useful from the spending, e.g., the infamous and (wrongly) maligned helicopter drop. Of course, if we have a choice, the public might as well get something useful from its spending rather than nothing at all.