Even if it could exist in this timeframe, how much would it cost? The issue I have with their viewpoint is that there doesn't seem to be any baseline for "good

Even if it could exist in this timeframe, how much would it cost? The issue I have with their viewpoint is that there doesn't seem to be any baseline for "good enough" that is short of absolute perfection forever (assuming adversaries that will attack with perpetually increasing sophistication.)