There's only about an infinite amount. I could easily claim that Picasso's main purpose was to create art. That has nothing to do with raising a family. Sure, the bajillions of dollars artists make can feed a family, but they could have opted for other forms of income, raised a family, and not made anything in the art world. How about Tesla? What if my purpose is to demonstrate decentralized fuel production? I don't see anything there directly related to a healthy family. Again, there are nearly infinite examples.