Check out the Wikipedia definition of "mass murder" [1] and then compare that list to [2]. Many of his approved drone strikes' civilian deaths exceed the "mass murders" on the wikipedia list of mass murders.

Quote from Obama [3]: "Turns out I’m really good at killing people. Didn’t know that was gonna be a strong suit of mine."

[1] https://en.wikipedia.org/wiki/Mass_murder

[2] https://www.cfr.org/blog/obamas-final-drone-strike-data

[3] https://www.businessinsider.com/obama-said-hes-really-good-a...