There’s a huge demand for them.
Where there is a big-time demand for something, legal or illegal, there’s gonna be somebody to supply it.
That’s simply the way market economies, even the Black Market Economy, operate.
Hundreds of billions of dollars worth of narcotics are bought and sold every day. When there’s that much money involved and an interruption in the methods of distribution of drugs happens, dealers must find new ways to deliver the goods.