The US doesn’t have an established history of firemen homelessness. The homeless vet abandoned by a stingy and heartless government is an established trope in American culture. That’s not remotely true for firemen. Calling out veteran homelessness is a useful tactic, people do it because it can cut across the normal boundaries of partisan politics.

Also, there technically have been a few military attacks on the US within the past century but they were not especially effective. During WW2 the Japanese military hit the US west coast a few times in submarine attacks, they also had a campaign of balloon bombings which killed a number of people in Oregon.