Adolf Hitler (1889-1945) came to power as the head of the National Socialist German Workers Party (the Nazi Party). He first gained power as Germany's Chancellor in 1933 before naming himself the Führer from 1934 to 1945. He was imprisoned after attempting a coup d'etat in 1923, but eventually rose to power through his political leanings supporting anti-Semitism, anti-Communism, and anti-capitalism mixed with a zealous support of totalitarian pro-Germanism--all backed by his rousing oratory skills and mass propaganda. He rebuilt the German armies, who responded with blitzkrieg attacks against the other European nations, beginning with Poland, and Germany eventually controlled all of mainland Europe.
Benito Mussolini (1883-1945) rose to become Prime Minister of Italy in 1920 and eventually achieved a rank of power equal to that of the Italian King Victor Emmanuel III. Mussolini was one of the founders of Facisim, and he managed to coexist with Hitler's Nazi Germany until his fall in 1943. Like Hitler, Mussolini was a charismatic speaker who used widespread propaganda and censorship to maintain power.
Joseph Stalin (1878-1953) took control of Soviet Union politics following the death of Vladimir Lenin in 1924. He became the General Secretary of the Communist Party in 1922 and ruled the nation with an iron fist until his death. Stalin eliminated all personal opposition to his rule through execution, deportation and exile to Gulag internment camps. He also turned the Soviet Union into a modern, industrialized nation. Initially, Stalin allied the Soviet Union with Nazi Germany, but when Hitler violated their non-aggressive pact and invaded Russia, the Soviet Union joined the side of the Allies. Following his death, the Soviet Union officially denounced Stalin, whose tyrantial reign caused the deaths of millions of civilians.
Anytime you carefully study someone who declared themselves to be the sole leader of a country's government and political system, you will first find a person with any incredibly huge ego.
The ego factor with a dictator is so critical to their claim to power. You will notice the traditional paradigm when a dictator comes to power. Look at Mussolini: He did not rise to power because a group of his sociopathic followers pushed him or twisted his arm; trying to find a way to convince him to seize absolute power.
When a dictator like Hitler rises to power, it's fueled by the person's belief that they are the only person in the whole country who is fit to lead them to greatness. Their ego keeps them in power because they believe in their own mind they are such a great leader and the only one in the whole country who knows how to deliver what is required for the country to achieve greatness, and then remain on top.
All of the foregoing convinces a dictator that no one else is capable of doing great things for their country. Ergo, if that is true, then he must remain in power indefinitely. His political cronies also come to believe the country cannot survive without this visionary, egomaniac at the helm.