It's politically unpopular to vote against defense spending or to decrease defense spending, also military service is fetishized to a high degree. It's generally a winning political strategy to put forward nationalism as patriotism. There is so much defense spending it's like welfare spread out to all the states in the form of defense manufacturing, and we have military bases in economically otherwise not very useful areas. This entrenched political base has proved to be impossible to reform due to the outsized political influence of those rural, thinly populated areas in the Congress and presidential elections.