Looking for something with high demand and low supply?
In his famous book, How to Win Friends & Influence People, author Dale Carnegie suggests that all human motives are based on a fundamental need of human nature; to gain a feeling of importance. (I would prefer to call it a feeling of purpose*). He goes on to argue that "one of the most neglected virtues of our daily existence is appreciation." My interpretation is this:
There exists a fundamental need in human nature, which is in high demand and has low supply. It providesa known means for which we can help people live happier and more fulfilled lives. Producing the supply is a great way to do business.
*I believe a feeling of purpose is what we're all really searching for, whether it be consciously or unconsciously. We want to have lived for a reason, to have made an impact on people's lives, to leave the earth with a sense of purpose and peace of mind.