I know you don't want to hear this. You need to find your own niche and create solution for it. There are so many different industries. Manufacturing for example, has more I maybe 1000 different sub/niche industries. As you get involved with these companies, you will find your software and sell to those in need of the solution.

Look into accounting, manufacturing, wholesale, b2b. Ancient dinosaur industries with very small movement because of the monopolies. Keep your eyes open, it is not easy, if it were, everyone would be a millionaire.