The Prince, Machiavelli

And it is worth noting that nothing is harder to manage, more risky in the undertaking, or more doubtful of success than to set up as the introducer of a new order. Such an innovator has as enemies all the people who were doing well under the old order, and only halfhearted defenders in those who hope to benefit from the new. This [reluctance] derives partly from fear of opponents who have [precedence] on their side, and partly from human skepticism, since men don’t really believe in anything new till they have had solid experience of it. This is why, whenever the enemies of a new state have occasion to attack it, they do so furiously, while its friends come only languidly to its defense, so that the whole venture is likely to collapse.^†

— Niccolò Machiavelli, The Prince, VI, 1513.

^†Machiavelli, Niccolò. The Prince: a new translation, backgrounds, interpretations. (A Norton critical edition) Translated and Edited by Robert M. Adams. New York: Norton, 1977.