At least the physicists' models let you land on Mars.

And an accurate, predictable model of economics would pay for the trip.

I don't think interplanetary travel will ever make economic sense. It's for other reasons that we reach for the stars.

Depends on your definition of economic success. If you define it as the ability to distribute resources necessary for survival, and extend that to the species, then interplanetary travel is the only eventuality that makes economic sense.