The lands taken from Germany ended up creating pockets of German speaking areas in surrounding countries. This was an amazing opportunity for the nazis to claim these lands and set up false flags operations.
That alone wasn't the cause: what enabled their success (as far as their ability to rebuild their war machine) was the ineffectiveness of the enforcement of those reparations, and the victors simply allowing the German economy to build more war materiel. Debilitating reparations can be done, but you have to maintain military power and use it to prevent the losing nation from refusing to pay, or building up its military again. The victors failed to do this and the result was another war. Honestly, I'm not sure what they were thinking. It's like throwing people in prison with hard labor for a crime, and then leaving the prison doors and gates wide open and firing all the prison guards and expecting the inmates to not escape.
The astronomical reparations Germany had to pay.
The lands taken from Germany ended up creating pockets of German speaking areas in surrounding countries. This was an amazing opportunity for the nazis to claim these lands and set up false flags operations.