If you're willing to expand the definition of "saving lives" to include people who would otherwise be thrown into prison and enter into the cycle of violence, recidivism and minimal job prospects, then your plan would literally save millions of lives. And when you consider that drugs are used to finance some seriously bad shit around the world, the number of "lives saved" grows even further.

According to Wikipedia, it's 120,000 alone in Mexico's recent drug war. Colombia has been one of the most violent places on earth for decades now. And it's not a coincidence that we're dealing with terrorism threats from the country that produces 70% of the world's opium. The number of people who've had their lives ruined by illegal drugs goes way beyond those that consume those drugs.