Announcement of New missiles in North Korea

On April 25th, four missiles including new three types were announced at seventy-fifth army's anniversary parade in North Korea. These missiles' range are so long and they can attack Guam where is American installation. Why did they use a lot of money for weapons such as missiles? Why don't they use these mony for happiness of people or world peace? I think this is the big issue of not only North Korea but every countries which have their armies. Should we really have armies and weapons? Should we really fight each other? Don't we really have another way?