Gauging The Cost Of Vigilance

One scientist studying the risk of asteroids striking Earth is arguing against increased government funding to find more of them.  He points out that NASA estimates we have already found 90 percent of the big ones that could do catastrophic damage, so the ones we'd likely find with increased funding would be smaller ones that don't pose much danger, anyway.

It's a reasonable argument, if, perhaps, a bit too intellectual.  Yes, while the danger posed by asteroid collision is real, it's also unlikely that such an event will cause any loss of human life in the foreseeable future.  That said, however, the Chelyabrinsk fireball explosion resulted in over a thousand people injured by flying glass.  It's only luck that none of those was fatal.  And yes, better building codes would help, but if you argue the danger is not enough to justify increased funding to find these rocks, it's hard to argue the danger does warrant toughening building codes around the world, which would increase the costs of construction, maintenance, and retrofitting.

Establishing an observation program to find potentially dangerous asteroids would not be costly.  The only real cost would come if we found a body we needed to deflect.  At that point, the cost of a deflection mission would be far less than the cost of allowing nature to take its course.