Ten years is (if he's extremely lucky) a tenth of a guy's life. Taking away a tenth (or twentieth, if parole is to be considered) of a guy's life for the second time he robs with a knife, gun, or bat, and injures no one -regardless of the extenuating circumstances- seems reasonable to you?
We don't try to rehabilitate people in US prisons, or treat them like humans with problems. All we know how to do is lock people away in hopes of either breaking them or at least just keeping them far away from us. It's our only tool.
Then of course we are shocked and dismayed when somebody, even after such a long sentence, re-offends. So what if they have learned no life skills in prison except how to use violence, and have no job prospects. Better lock 'em up longer next time. That'll teach them!
Rather than say "injures no one - regardless of the extenuating circumstances", you could say "injures no one - through sheer dumb luck". If you point a gun at someone, it could easily enough go off without your planning it.
I do agree that removing the possibility of parole is a bad idea.
Firearms don't "go off" unless you pull the trigger. They also don't "go off" if you drop them; Federal standards and rigorous testing to the same ensure that.
As long as you practice appropriate trigger discipline [0], your firearm is no more dangerous than a club.
Quite. And one can always count on nervous 19-year-olds to practice appropriate trigger discipline.
As for dropping them, the .45 pistol the military still used 30 years ago, could do that. But no doubt they are all off the street, or at least the discriminating felon won't carry them.