Comment by LorenPechtel

More generally--the cost to eliminate bad outcomes goes up exponentially as you deal with the easy bad outcomes. Credit card fraud is simply one example.

Or consider a simple non-financial example: I left half a dozen pears on the tree this year--getting those last few pears would have required hauling a 50 pound ladder around the house and then struggle with setting it up. (Due to it's size it's a lot harder to handle than it's weight indicates.)