Customers are the reason why businesses exist. A business without a paying customer is at a dead end. In due course, it will meet its ultimate end. As seemingly superb an idea may be at the startup stage, it can only be as great as it becomes while informing, transforming or serving the targeted receiver - which in this case is the customer. This is to say that for a successful entrepreneurship venture at the startup stage, the customer not the idea is paramount. Emphasis however should made later on who is a 'paying customer' because what the business need is not just a customer but a paying customer.
Most times as a startup consultant in our mini firm in Nigeria, we have had a lot of young and aspiring entrepreneurs walk up to us excited with their so-called super ideas that can transform the world in a giffy. We get excited all the time to work with these sets of people because in most cases proper market diagnosis not only get to prove otherwise but also throw open to us new sets of realities and how we can address them from the customers' perspective. We end up in most cases not executing the original plan but a new variant or deviation which at best is sure to penetrate the market, break even and make profits.
Kaytech Digital Solutions which today provide a web portal-like platform for some primary and secondary schools in Nigeria was one of those overturning cases we handled that came from an enthusiastic young entrepreneur with a 'super idea' to build the first ever locally manufactured mobile tablets in Nigeria (some years back). Eagle's Platform Multi Concepts International is also one of those cases we handled that started as a motivational center but are currently engaged as a weight loss and fitness center helping scores of obese people to cut down their weight and regain fitness naturally without drug while also adopting a calendar best fit for each of their clients.
These examples give credence to the fact that the ideas are not paramount and hence must be market-driven to be successful.
Until you get a paying customer, you are yet to start a business!