He omitted nothing. You are not paying attention. He said the cost was ten percent.
For what ever amount paid for law enforcement to achieve a certain reduction in drug usage, the same level of reduction can be achieved through noncriminal treatment programs at ninety percent less cost.
Treatment costs only 10% of what enforcement costs for any dollar amount you wish to throw out there.
Better still, no Great Grandmothers need to die.
You are assuming that the relationship is linear, which is not likely to be true. It never is when discussing the marginal utility of money.