If you want to make a moral difference between soldiers and other people in dangerous occupations, you might consider making it on the basis that soldiers have to deal with threats to their lives that are caused by other people's deliberate hostile action.

Disagree. I think the relevant difference is people risking their lives providing a service that's (at least believed to be) a public good. Notice that the two civilian jobs that are also frequently called heroes are police and firefighters and your criterion doesn't apply to the latter.