While you are at it, just how did Max Cleland receive his war wounds. also like to know the extent of Kerry's. Just curious
All of your questions have answers in the public record. But, to be quite blunt about it, "they were there" and "others weren't". You don't have to be a Kerry or Cleland fan to respect the difference.
War is war and those who were in-country could get hurt at any time for any number of reasons. Some died.