Terrorism is a black swan (rare high impact) event.

No, it's not. The biggest terrorist event ever is... what, 9/11 with something like 5k deaths? That's not high impact by any means. Annual variations in flu virulence outweigh that.

Consider attempting to estimate the danger of asteroid impacts or rogue AIs by looking at the last several millennia of data

One of those is not like the other, one of those does not belong.