Why did Nancy Pelosi say it would be cheaper to treat drug abuse than stop it at the border?

“Well if your question is about drugs, I’m for reducing demand in the United States,” said Pelosi. “That is what our responsibility is on this subject. The RAND Corporation a few years ago did a report that said it would be much less expensive for us to, through prevention first and foremost, but through treatment on demand to reduce demand in our country, is the cheapest way to solve this problem