Because Germans were invading aloy of places and killing alot of different ethnicitys and then America stepped in and got involved
Because Hitler wanted to take Germany away from the global banking system and have their own economy. Churchill actually said "We are waging war on Hitler whether he wants it or not" when he found out about this. That was long before Germany started to invade other countries. Only God knows what really led to the horrible outcome of WW2.
money trade systematic malfunctions unable to maintain economic stability