That's because Hitler kept winning. He militarized the Rhineland in 1936, the allies did nothing. He took over Austria in 1938, the allies did nothing. He occupied Czechoslovakia later the same year, the allies did nothing. With every win, Hitler's popularity increased at home. He's reported to have been quite surprised when the allies finally declared war after Poland.

We have a word for this: https://en.wikipedia.org/wiki/Appeasement

Neville Chamberlain negotiated with Hitler over handing Germany large swaths of Czech territory critical for border defense. The Czechs weren't invited to the conversation.

https://en.wikipedia.org/wiki/Peace_for_our_time

We know how that turned out.