How did Hitler get started in politics?

Hitler became a politician after being a solider in WW1 who was unhappy about how soldiers were treated. He wrote Mein Kampf the story of his struggle/life. Before he became a solider he tried to be an artist in art schools in Vienna, but was refused because he wasn't good enough. His art now sells for hundreds of thousands of pounds. The bad experiences of his younger years caused him to want to make a difference. Perhaps if his past had been kinder to him, he would not have took part in genocide that shocked the world, perhaps WW2 wouldn't have even happened. He was deeply unsatisfied that Germany lost the WW1 and he wanted to get back at Britain. This meant that he needed to have another war to get his revenge.