Most people who start a business opt for businesses where they see others succeeding . The over subscribed actually attracts more interest. Sometimes they might gravitate towards a service they are passionate about or are very good at but on the whole high profile areas attract more recruits.
Those entrepreneurs who do best however are able to spot a gap in the market which is hidden from the casual observer. I would suggest that there are two ways you might develop an eye for an opportunity.
Firstly think of all the times you have been frustrated when purchasing a product or service. It is out of these frustrations that the core of a new business idea can grow. The market tends to have traditional ways of doing things which become in efficient over time. Scientists might define this as entropy or the ability for order to turn to chaos and the commercial world is no different.
The second way to spot a gap in the market is to do the very thing I have mentioned earlier. This evokes a strange paradox. If you want to find a gap in the market go into an oversubscribed business and find a way of doing a common thing better. Insurance is as old as the hills but when direct telephone quotes came in, the early adopters made a fortune. Coffee shops are two a penny but the first to deliver coffee to people attracted massive of custom.
The point I am making is you don’t need to come up with sometihing completely new just slightly adjust what is already in existence.