If you're not failing every now and again, it's a sign you're not doing anything very innovative.
If you or me go to the gas station to fill up our car and it costs us much more than we expected, it will zap our discretionary income. We won't have the extra money to buy that washing machine or new winter coat-all big ticket items that are important to economic growth.
Hope is a state of mind, not of the world. Hope, in this deep and powerful sense, is not the same as joy that things are going well, or willingness to invest in enterprises that are obviously heading for success, but rather an ability to work for something because it is good.