I think this is where it's worth differentiating between different types of "believes in" (and why I think modal logics are cool). I can convince myself that a thing seems safe to believe, or I can tangibly believe it, or I can believe it in a way that allows me to confidently manipulate it, or I could even understand it (which you could call a particular flavor of belief). Practical use seems to fit on that spectrum.

I certainly don't believe in black holes in the same manner that I believe in the breakfast I'm eating right now.