There's a couple of other ways to make money. One is to entertain. Entertainments drives a big part of the online economy. Music is BY FAR the most popular niche on Youtube. Gaming is also huge. And there's plenty of other entertainment related niches/markets that are profitable.
Another option that can be profitable other than "solving a problem" is collectibles. Many people have a deep urge, almost an addiction to add to their collections. I knew someone that collected everything with geese on them. She had clothes, pot holders, dishes, cookie jars, furniture, figurines, art and everything else you could think of with geese...and she spent a lot of money building her collection. There are tons and tons of possibilities for collectibles.