If cocaine was in widespread use, in 1900 and was even put into Coca-Cola, why did government make it illegal?

If it is illegal, they can control it. Think about it - the police are supposedly there to protect and serve, the question is who? The people or Govt.? At present the answer is Govt. making the country a huge police state but nobody will acknowledge this or even realize it. I am not being pessimistic, rather realistic here. The police govern the country under whose laws? If they really serve the people, what will happen if the same people decide they are no longer in favour of the present Govt.? Will the police stand with them? Will they be allowed to protest peacefully? Will Govt. intervene and ask for violence so as to disrupt everything and justify police brutality? Seems like Govt. are not for the people, by the people anymore and Orwell's "Animal Farm" correctly described it.