This:

"A democracy cannot exist as a permanent form of government. It can only exist until the voters discover that they can vote themselves largesse from the Public Treasury. From that moment on, the majority always votes for the candidate promising the most benefits from the Public Treasury with the result that a democracy always collapses over loose fiscal policy always to be followed by dictatorship.

The average age of the world’s greatest civilizations has been 200 years. Those nations always progress through the following sequence:

From bondage to spiritual faith,
from spiritual faith to great courage,
from great courage to liberty,
from liberty to abundance,
from abundance to selfishness,
from selfishness to complacency,
from complacency to dependency,
from dependency back into bondage."

–Alexander Fraser Tytler Lord Woodhouselee (1748-1813), "The Decline and Fall of the Athenian Republic", Scottish historian at Edinburgh University

And. alternately, this:

In “Democracy in America” Alexis de Tocqueville wrote almost 200
years ago, "the American Republic will endure until the day Congress
discovers that it can bribe the public with the public's money.”