The more you invest in increasing your knowledge, the more you get in return.
Learn a little, become a little more productive, get a few job opportunities. Learn a lot, become lots more productive, get lots of job opportunities.
Knowledge has a cumulative, accelerating quality to it.
Contrast with most production processes, which exhibit the opposite quality of decreasing returns. For most type of production processes, whether it is farming, manufacturing, or services, as one invests more and more resources, the marginal returns get smaller and smaller.
— Origin of Wealth by Eric D. Beinhocker