Democracy is rule by those who can most influence the masses. This includes the media, news, entertainment, education, and similar positions. Once those roles have been centralized, the politicians get better returns by satisfying those owners instead of the public.

The rotating circus of politicians also means that you cannot hold elected officials directly accountable. By the time the public learns somebody made a massive mistake, they can be out of politics for many years. This leads to massive unaccountability to the general population and only accountability to the centralized money holders.