Why you should solve a problem that solves other problems

The best problems to solve are those problems that solve not just one problem, but several other problems. For example, if we find a way to create an intelligent machine, that machine will solve a lot of other problems we have because it is smarter than us. It can build the best car, it can cure cancer (if there is a cure), and it find a way to feed all humans. But building such an intelligent machine is damn hard, so maybe you should find another problem to solve.
One such problem is oil. When two of the original founders of the electric car company Tesla Motors, Martin Eberhard and Marc Tarpenning, wanted to find a problem to solve they decided to solve the world's dependency on oil by building electric cars [Source]. 
Solving our dependency on oil is one of those problems that will solve a lot of other problems, such as:
  • We have to import oil of "troublesome" countries, like Saudi Arabia and Russia. Sweden for example imports maybe 40 percent of the oil supply from Russia. And what is Russia doing with the money? Yes they spend the money on weapons. And a few years ago, Russia decided to practice targeting a Swedish naval base with nuclear weapons. Is it really a good idea to pay another country money and get that response?
  • Another problem is that oil causes global warming.
  • We are also going to run out of oil anyway, so we have to solve this problem in a not that distant future.
  • The number of cars increases each year, so even if there is an endless amount of oil, we can't supply all new gasoline cars with the oil we are currently pumping up.