Those numbers are made up to support your assumptions. I claim the troublemakingest 5% have an increased chance of having an outsized negative effect on overall society, and by tossing them by their ears, we double their chances of behaviors that have serious (10X) negative effects: perpetrating fraud, abuse, or violence.

Depending on assumptions, it is easy to argue that money is best spent accelerating our brightest minds and giving extra support for the most at-risk, letting the middle atrophy. Or it is best to treat everyone equally, which certainly leaves the top underfulfilled and the bottom underprepared. It's just spitballing.