Once Hitler talked Germans into handing over their sick, deformed or mentally ill relatives over to him for disposal he knew he could get them to do almost any other horrible things.
Actually the T4 program was the only time the German people resisted Hitler.
As long he was killing off elderly and sick Jews it was ok.
It was when he went after non Jews that Germans protested.
Still you’re right.
He killed off about 70,000 in a dress rehearsal for the Holocaust.