“… the very principle of constitutional government requires it to be assumed, that political power will be abused to promote the particular purposes of the holder; not because it always is so, but because such is the natural tendency of things….”
– J. S. Mill (1861) 
Two very wise men provide warning to us today.
Voltaire (in 1764): “In general, the art of government consists in taking as much money as possible from one party of the citizens to give to the other.”
Bastiat (in 1848): “The State is the great fiction through which everyone endeavors to live at the expense of everyone else.”
And now a 21st century observation:
“When government undertakes tasks for which it is ill equipped it squanders the authority necessary for carrying out its core responsibilities. Pervasive rent-seeking, bad for our economy and worse for our republic, should be discouraged instead of rewarded. If government becomes integral to securing every advantage and assuaging every grievance, then governance becomes impossible.” – Richard Voegeli 
And wisdom from the Marxian-turned-free-market economist Thomas Sowell (1930–):
“No one will really understand politics until they understand that politicians are not really trying to understand our problems. They are trying to understand their own problems–of which getting elected and re-elected are number one and number two. Whatever is number three is far behind.”
“The government is indeed an institution, but ‘the market’ is nothing more than an option for each individual to choose among numerous existing institutions, or to fashion new arrangements suited to his own situation and taste.”
“One of the most pervasive political visions of our time is the vision of liberals as compassionate and conservatives as less caring.”
And some insight from the Nobel Laureate in economics, James Buchanan (1919–):
“Public choice [economics] rejects the notion that the state is wiser than individuals.”
“Government policy emerges from a highly complex and intricate institutional structure peopled by ordinary men and women, very little different from the rest of us.”
“Government agents are not seen as pursuing some nebulous ideas of the ‘public interest’; they are seen, rather, as pursing their individual self-interest in a governmental context.”
And a few more salient quotations:
“The influence of special interests is now at an extremely unhealthy level. And it’s to the point where it’s virtually impossible for participants in the current political system to enact any significant change without first seeking and gaining permission from the largest commercial interests who are most affected by the proposed change.” (Al Gore)
“When buying and selling are controlled by the legislature, the first thing to be bought and sold is legislators.” (P. J. O’Rourke)
And finally, from F. A. Hayek on the dangers of majority politics:
“To act on a behalf of a group seems to free people of many of the moral restraints which control their behavior as individuals within the group.” (F. A. Hayek)
 Quoted in James Buchanan, “From Private Preferences to Public Philosophy,” in Politics as Public Choice: The Collective Works of James Buchanan (vol. 13) Indianapolis: Liberty Fund, 2000, p. 41.
 Richard Voegeli, “Reclaiming Democratic Capitalism,” Claremont Review of Books, Spring 2012, p. 46.
That’s a nice collection.
You may rest assured that I will put several of these salient quotes to good use.