I really hate that quote, because people are horrible about quoting only that one section. I find it really funny too, because people say Hitler claimed it was the only way, when the quote even starts with the word "alternatively". He actually proposed two ways, completely opposite of one another.

The first was to just ignore them. He knew his views weren't popular from the get-go, and he wouldn't be able to hold onto moderates. On the flipside, he knew that crushing the leaders before moderates joined would kill the party.

Can't debate them, can't reason. People did try to counter at first btw - using their words. How'd that go?

Ah, this is what Hitler realized, and precisely what he used to win. You can't debate or reason with fascists, but you can with their moderate supporters. These moderate supporters merely wanted the economy fixed, and he was only the one pointing out it was broken. He counted on nobody bothering to pay attention to the moderates, and instead focus on the fascism. Lumping everyone together as fascist and screaming "antisemite" at all of them just seems like further ignorance to the moderate's concerns. Once those moderates join and become calloused, your only option is nuclear.