Define careless. . . Some people might find justify the use of a gun in different ways. A lot of people would say that shooting a rapist with a gun is justified. Others would say that guns should only be used for hunting. Then there's the sick few who would shoot the faces off of girl scouts... how many points should be deducted for that?
Careless would be not keeping the gun secure, maintained and leaving it loaded. IMHO.
Naturally using a gun in a crime would get you to loose your license for good.
Unfortunately we can't predict psychotic behavior 100%... but I hardly think if the collumbine kids had to go through training, registration, waiting periods and such, then the attack would have happened. At least not to the degree that it did.
What about using the gun for self-defense? Allowing guns for self-protection against people with guns is illogical, because if no one had a gun, then no one would have to defend themselves against others with guns. That much is obvious.
That much is silly. You will never rid the USA of guns, making them illegal only makes them underground. You would still worry about gun crime because criminals don't care about illegal guns. (most guns used in crime are illegal anyway).
What we need is better and stricter management of guns that we already have and that are produced in the future. There will never be an gunless utopia in the world.
We need workable solutions, not daydreams or finger wagging.
wa:do
ps. even the wiki article on Collumbine will tell you where the kids actually got the guns and from whom.