Hitler botched things up by grabbing all of Czechoslovakia.
Had Hitler stopped at the Sudetenland, he could have made the case that he was not an imperialist, that he did not wish to rule over any non Germans and that his ambitions were limited to that. He could even have rightfully argued that the Austrians and the Sudetenlanders wanted to be part of greater Germany. There’s no doubt unification would have won any free and fair plebiscite had one been held in those areas.
But....what is now the Czech Republic had been the center of heavy industry - particularly armaments in the Hapsburg Empire. Hitler especially wanted the massive Skoda works. Getting it undeniably strengthened Germany a good bit.