There are several flaws in your argument.
US agencies place a $5-10 million value on an American life [1]. This is not the value of a life anywhere, though. For example, part of the valuation comes from discounted earnings calculations, which is lower in lower-income countries.
Furthermore, just because problem A is worse than problem B (measured in dollars) doesn't mean we should spend more money fighting problem A. Money should be spent where it has the greatest impact.
[1] http://www.nytimes.com/2011/02/17/business/economy/17regulat...