Your quote from Alexander TYTLER is apparently a misquote:
http://en.wikipedia.org/wiki/Alexander_Fraser_Tytler
A democracy cannot exist as a permanent form of government. It can only exist until the majority discovers it can vote itself largess out of the public treasury. After that, the majority always votes for the candidate promising the most benefits with the result the democracy collapses because of the loose fiscal policy ensuing, always to be followed by a dictatorship, then a monarchy.is entirely consistent with Alexander Fraser Tytler's published views on democracy in general and Athenian democracy in particular (he was a Professor of Universal History and Greek and Roman Antiquities as the Wikipedia article you cite points out), and represents not a misquotation, but simply a quotation for which our best historical attestation is at some remove. The misquotation -- not reproduced in the post -- is the appending of a description of moral stages of rise and decline in democratic polities written sometime in the 1940's -- to Peterson's Tytler quote with the stage of monarchy removed.
It is also the case that whether the quotation originated with Tytler or with Peterson, the analysis it presents has been borne out time and again throughout (and is being replayed in Athens yet again -- though whether the dictatorship will be one imposed from Brussels or one lead by the Golden Dawn movement remains to be seen). Of course, since Tytler's time, the monarchy stage seems to able to be short circuited provided there are surviving external democratic polities with enough political clout to push democracy back onto societies exiting the dictatorship phase.