The Wealth of Nations by Part 1 Chapter 10 Page 24

Many people possess them in great perfection, who disdain to make this use of them; and many more are capable of acquiring them, if anything could be made honourably by them.

The overweening conceit which the greater part of men have of their own abilities is an ancient evil remarked by the philosophers and moralists of all ages. Their absurd presumption in their own good fortune has been less taken notice of.

It is, however, if possible, still more universal. There is no man living who, when in tolerable health and spirits, has not some share of it. The chance of gain is by every man more or less overvalued, and the chance of loss is by most men undervalued, and by scarce any man, who is in tolerable health and spirits, valued more than it is worth.