When I think about this quote, I find that it may become true. If things continue the way they are, a World War III and IV could easily be triggered. This is the way I thought of how think it's possible.
World War I was fought with tanks, grenades and guns and other not-as-destructive weapons, leaving America wealthy and others unfortunate. This eventually led to the rise of dictators and the start of World War II. This war was more lethal than any other war. Fought with poison gasses, fighter planes, and the worst of all, the atomic bomb, there were casualties by the thousands.
So what will happen if there's a World War III? What would we fight with? Due to new advances in technology, World War III could be fought with deadly weapons. This war could be a nuclear war, destroying and unnecessarily ruining lives. Most of humanity will no longer remain on earth, and most of the earth would practically useless to survivors.
After this, a World War IV could simply be started with people fighting over resources and supplies. However, there won't be guns and tanks. The only things that they could fight with then are sticks and stones.
