Our speaker is either the world's biggest idiot or the world's most sarcastic pacifist. Take your pick.
If our speaker really means what he says—that it doesn't matter if you lose your legs or your sight in battle because people will be nice to you and you can forget it all at the bottom of a bottle anyway—well, he's got another think comin'.
Frankly, we wonder how anyone could really think that about wounded veterans coming home from the front, so we find this to be a rather unconvincing reading of the speaker. No one's really that dense.
But collectively, the world can be that dense. It's easy for society as a whole to ignore the plight of veterans, while individual people may care and understand. So perhaps this poem is really about the frustration Sassoon experienced with society on the whole, since no one seemed to be acknowledging or understanding the cost of war in the public arena. Which brings us to…
…the other reading of the speaker—as a deeply sarcastic, deeply pissed off guy. That's who Shmoop really thinks this man is. As he asks rhetorical questions of the wounded soldier, he attacks, point-by-point, the callous lack of awareness that the folks the soldier has come home to show. He's not asking if these things matter—he's telling us that they do.