What do you use a personal budget for?

I'm working on sort of an early-stage idea for a personal budgeting product. So far, its main feature is going to focus on answering a single question: how much runway do I have? I wrote something rudimentary like this years ago when I adopted my first child, and it helped me make it through the rough financial patch(es) that followed with my sanity in-tact.

The question is, then, is just answering the one question enough of a value proposition? I don't think it necessarily is, so I'm trying to build on the idea to get people to the point of wanting to commit the time to enter the data/credentials the engine will need to make accurate predictions.