Why was hitler so powerful?

Hitler had many advantages. The Germans were resentful and wanted to take revenge post WWI and the Treaty of Versailles. Hitler took advantage of the discontentment of the masses and promised them revenge and a better future. He also instilled in them a sense of superiorty by declaring them Aryans. That' why they supported him plus he was ambitious, a charmer and a charisma. That really helped.