I've read a lot of WWII history. Especially focused on the ETO and Germany. In my mind, it seems beyond clear that Hitler was the reason that war broke out, the single prime key motivating force, his desires, his influence, his decisions, his cult of personality, his charisma, his quirks, his obsessions, etc. He existed and acted within a framework of other facts, within a certain context, and there were plenty of others who failed to act against him, enough, early enough, when it would have been more effective. But I've been confident of the "because Hitler" idea for a long time.
If you can point me at a history book or analysis which you think contradicts that, definitely share it with me, I always love to learn different angles. If I were to give you just one that aligns with "because Hitler" I'd recommend Shirer's Rise & Fall.