They just took 33 grams and divided by 2 mg which is the typical cited lethal dose of fentanyl to get 16,500. When dosed correctly it would kill zero people. But when you’re dealing with such tiny amounts in the microgram range that drug users/dealers can’t reliably weigh and make errors, unknown potency, differences in people’s tolerance, yes it’s quite dangerous and deadly. 100 times more potent than morphine. Would that batch have killed 16,500 people in reality? No likely not. But they did say “at worst” in fairness. So yeah assuming that’s the weight and one hundred percent potent divided into exactly lethal doses given to opiate niave people and perfectly doled out all at once that’s about how many it could kill. Cops also could be lying about weight, or it may be cut with something and not pure. I’m certainly not trying to argue for the war on drugs which I very much disagree with or against your other points, but that’s where that number came from. And it is a very dangerous drug because of its high potency with dosing in microgram ranges and often unknown purity.