A possible defense of Chamberlain remembers that, at the time, it was not yet 100% clear which was the greater threat -- Hitler's Nazi Germany or Stalin's Soviet Russia. Even Churchill seemed occasionally of two minds on this.
At the time, many were happy to contemplate the idea that Hitler might invade Russia and destroy the Communist infection there.
Indeed, even today, people like Pat Buchanan argue the only real problem with Chamberlain's appeasement policy, was that he dropped it after Czechoslovakia, and issued a war guarantee to Poland. Buchanan says Europe would have been better off to give Hitler everything he wanted!
But it never happened that way, because after Munich, Chamberlain felt betrayed and humiliated by Hitler, and so took Churchill's advice not to let it happen again.
If you want the root cause at the core of the whole appeasement idea, I think it would go something like this: it's impossible to take a modern democratic country into a full scale war without ALL of its citizens support. And to get that support, the leaders must first demonstrate, they have walked the extra mile to settle things peacefully. That's what Chamberlain was up to, and not until after Munich did it begin to seem clear that his efforts must fail.
Sorry, my mistake. Buchanan does not say it, exactly. Imho he implies it, while at the same time insisting Hitler's actual aims were quite limited, and could have been achieved without war, except for clumsy British (especially Churchill's) diplomacy.
So, to Buchanan, the real villain of the story is not Hitler or Chamberlain, it's Churchill.