Are there heroes?  Without a doubt!  Some have died and some are still alive.  In most cases they are not "giving" their lives, they are just getting killed as part of a job they are being paid for.  However the mere fact a person gets killed does not transform them into a hero.  A tragedy to be sure, but so are all deaths no matter their nationality of the profession.  I view casualties are on-the-job deaths.  No different than the people who die to bring you Alaskan king crab, or build your high-rises, or farm your vegetables.  Some jobs just have more risks and whether due to economic, educational, or ideological reasons some people gravitate toward those professions.  We can mourn them or honor their lives without the label.

I think we use "hero" to make us feel better about the death.  Using terms like "sacrifice" makes it almost palatable, even romantic.  That is not the reality, the person did not think "I am now going to willingly die for this particular idea", in most cases it was just bad luck.