How to Find a Million Person Problem:
Note: it’s not necessary that it’s a “million person” problem . . .but I refer to it that way to indicate that you may want to choose something that can help a lot of folks . . .
But if you have a highly specialized idea, with a small crowd, then the key is to make it very powerful so you can reach as much of the market as possible, and perhaps be willing to branch outside of the exact topic or strategy.