The most important factor to consider when starting to build a business is the target audience. You have to think of who would you want to cater to. Who are the communities that you may profit off of. Like for example if there is a school near you, you should know that students would be your target audience. You should start a business where students can buy materials from or a place they can study or even hang out around. I believe that if you studied your target audience, the first step of your business is already successful enough.
I'm thinking you are a student, your first area of taught suggested a solution for a student based area and now I want to put it to you having notice this, that's an opportunity you can hop on if you want to because you actually can if you .ake some research further and come up with an ideal, since you already know your target it becomes easy pizzy for you to explore and make some profit providing solution to these students.
Anyways if I'm wrong, I beg your pardon. But the whole idea here is you have made a very good point and it can be used to create good business opportunities although this isn't the only factor that is needed to put into consideration but it is a key determining factor because it influence your product, your sales approach and even your advertisement. All of that will be affected by the target audience you aim at providing your services or selling your products to.