The problem with the "survivor bias" argument is that it allows for a lazy denial of actual trends in things: sometimes stuff does get worse.
The same applies to "every generation thinks the next generation is horrible". That may or may not be true, but sometimes there are horrible generations.
Even then Germany was a parliamentary system where the Chancellery goes to the biggest party or coalition in parliament. And the NSDAP was the biggest in the elections in 1932-11 and 1933-3. There were enough idiots who voted for Hitler and his party in those early years.
He got voted cancelour by a majority.
That is as democratic as it gets. And yes, this should attack anyones assumption that the people always vote for the best.
Thats why there are non-voted pillars of power in a good democracy, that can not correct a bad course, but can at least keep it in check.
The same applies to "every generation thinks the next generation is horrible". That may or may not be true, but sometimes there are horrible generations.