“A democracy cannot exist as a permanent form of government. It can only exist until a majority of voters discover that they can vote themselves largess out of the public treasury. From that moment on the majority always vote for the candidate promising the most benefits from the treasury…”
- Attributed to Alexander Tytler (unverified)
NB: For the latest data point on the above, being played out in the US as we speak, see the US Debt Clock—especially the Liability Per Taxpayer at bottom right.