In my experience, $50,000 only makes sense coming from friends & family. You'll burn through the cash quickly and likely won't reach a meaningful business inflection while spending that $50k. If you're just trying to get a prototype built, most angels and even accelerators will tell you to come back when you have something real and a few users/customers.

In short, they should figure out how to build it themselves or get some friends & family to pitch in to pay for the prototype to be built.