At age 16 he quit high school. At age 17 he applied for the Vienna academy of fine arts, but was rejected. When he was 14 his father died, and when he was 18 his loving mother had cancer. A Jewish doctor treated her, but despite costly and painful treatment she died. He was then 18, and alone in the world. .
He returned to Vienna, and quickly became penniless. He wandered in Vienna, slept in bars and in shelters for the homeless. His attempts to make a living as a painter were futile. He had two Jewish friends there, but Vienna was then an active center of strong antisemitism, and Hitler also read "The Protocols of the Learned Elders of Zion", a totally falsified document that was written by the pre-WWI Russian royal secret police in a cynical attempt to divert public blame of Russia's trouble from the monarchy to the Jews. The 'protocols' describe an imaginary conspiracy of rich Jews to dominate the world by dominating countries like puppets and turning them against each other. Hitler, already a typical anti-Semitic, believed every word.
In his poor six years in Vienna, Adolf Hitler developed his extreme hate of Jews, was exposed to the idea of anti-Jewish legislation, discovered his remarkable talent of speech, that used grand romantic metaphors from German culture and from his imaginative artistic soul, and developed his view of how a totalitarian state should be managed, following the example of Vienna's very successful mayor, who was also an anti-Semitic.
At age 24, still penniless, Adolph Hitler left Vienna and crossed the border to Germany in order to avoid military service in the Austrian army. He was arrested and brought back to Austria, but was then found "unfit, too weak, unable to bear arms". Given his later military service and bravery in combat, it's obvious that he successfully played a false figure in order to escape a peacetime military service he wanted to avoid.
When the fragile European balance of power exploded a year later into World War One, Hitler's German patriotism was ignited, and he decided to join the military.
