Post hoc reasoning is the basis for many superstitions and erroneous beliefs.
Many events follow sequential patterns without being causally related.
For example, you have a cold, so you drink fluids and two weeks later your cold goes away. You put acne medication on a pimple and three weeks later the pimple goes away. You perform some task exceptionally well after forgetting to bathe, so the next time you have to perform the same task you don't bathe. The sun returns, proving to you the efficacy of your action. You use your dowsing stick and then you find water.