Hitler wasn't elected. He was appointed Chancellor by President Paul Hindenburg in an attempt to collaborate and avoid a dominate NSDAP (Nazi) Party. With Hitler Chancellor, he was able to appoint more NSDAP members into the government, and eventually took total control shortly after the Reichstag Fire Decree.

So the people didn't really get to realize that they "fucked up." Hitler won 36% of the vote in 1932 election (which he lost to Hindenburg). However, after his appointment to the Chancellorship, he pushed through economic agendas, military revitalization, and used those combined with a strong propaganda campaign to swing the tide of the country more or less to his side.

Granted, this is 1933-1939ish before war had broken out. An average German (non-jewish or other lesser thans) would have had an upswing in the economy, wages, and pride. I'm sure there were people who knew what he was aiming at, but they were simply drowned out by the propaganda machine and NSDAP supporters.