As many have mentioned, the expected number of deaths is 1 for no action and 1.25 if you pull the lever. Many still choose to pull the lever despite the expected number being higher. As I understand it, the reasoning is that the value of reach outcome doesn't scale linearly with the number of people alive/dead. Going from 0 deaths to 1 death is a much larger drop in value than going from 1 death to 2.

Something something one death is a tragedy, a million deaths is a statistic.