People think of children as either sweet and innocent or too stupid to cause much trouble and both views are wrong. A child of elementary school age has the moral reasoning and impulse control of a racoon paired with problem solving equal to or superior to an adult’s, yet unbound by the shackles of cautionary experience or awareness of long-term consequence.
This is what allows the children to both create a black market in live bioweapons while still only valuing said weapons at 25 cents.