Only partially true. The people who grow opium crops are incredibly poor. They make very little from selling their crops on the market. They are not the ones profiting.
As I said before, the main reason they grow these crops is because in most cases, the land can not support any other types of crops. They are forced to grow it or die. Our only chance to stop the production is to help them with alternatives, such as non-narcotic plants.
It's true they are not making the big bucks, that comes from refinement and distribution. But they are making enough to give them incentive to grow it. It's a subsitence level profit, but a profit non the less.