What has happened? What has happened is quite simple. Those elements of the population which are both brutal and stupid (and these two qualities usually go together) have combined against the rest.
And another quote from Hannah Arendt:
Only the mob and the elite can be attracted by the momentum of totalitarianism itself. The masses have to be won by propaganda.
The problem might be that the "mob" is getting stronger for various reasons and there is an active elite that is eager to exploit them for their own gain.