Why do we try and keep someone alive when we know there's no chance he will live ?

A 98% burned man came into the hospital. So badly burned, his thighs were cracked open like hot dogs. Doctors and nurses worked for hours, de-briding his skin, giving him transfusions, etc.Whether he felt pain or not cannot be determined. He ultimately died. Why can't we just comfort him in his last hours instead of futile treatment that may cause him pain ?

Well, I'm not sure about doctors in that sence..
But I have experience with an really close aunt that passed away due to cancer..
She had brain cancer and we were told that Chemo was out of the question to help her because it woudln't help, but we could try by some miracle. Of course it didn't work and we took her out of chemo by the risk we didn't want to make her more sick.
We tried as hard as we could to get this pill that was still in testing, we never got it, she passed before, but we all had our hopes up that in some way this would help.
In the end we were saying "It's okay to let go, we don't want you in pain anymore." Her breathing was on and off, like she would be breathing then would just stop, when this happened we would all freak out and when she started breathing again we all had a sigh of relief..
We don't want to lose our loved ones.. Expecially those close to us so we do what we can to keep them alive.

Because doctors are so pro-life. If the guy didn't have a living will then they're legally obligated to try and save the guys life. Also family members because they're going through a trauma can't imagine life without this member (no matter what state he's in) and in a traumatic situation people don't think clearly. I think that quality of life is more important than quantity but if the guy didn't express his wishes in a living will then there's nothing the medical profession can do other than try to fix the problem.

i think because its the humane thing to do , where there is life there is hope .