Scientific evidence, mythology, some interpretation of religious texts all seem to indicate that a disaster of the type that may greatly alter the population of humans on earth will occur at some time. When this will happen will only be known when it happens. The militia attitude, hoarding supplies, building bunkers all seem to be quite absurd notions to me. Everything we need to carry on after such an event will be available wherever we are. Learn what you need to do. Then relax and enjoy your life today and every day. Worrying about what may or may not happen in the future is wasting time that could be enjoyed right now.