In this day, it's hard to think of a new idea that hasn't been implemented it. What you can do is find what people badly needs and offer that sort of service/goods. But, if you live in the city, people probably already have what they need/want so most businessmen look for other places. They research what that place needs and if the people can afford paying for that. Then see if it's actually profitable and doable.

You can also do the traditional way of investing which is investing in education. Even college graduates go back to school when they can finally afford to pay for the tuition fee to get a master's degree.