Are doctors really not motivated enough to treat seriously ill patients older than 70 years old?

I don’t think that has anything to do with the “older than 70 years old” part as much as the “seriously ill” part. As a doctor, sometimes you have to accept the fact that from a certain point on, any practice and medication, and trial might prove ineffective, and it might only cause more suffering in the patient. I don’t think doctors give up on treating patients until they have done everything they can. Or at least, I’d like to think so because it is both morally and professionally unacceptable to give up without exploring every possible option. In the end, it all comes down to the health condition of the patient, not their age. The reality is not all patients are lucky, and that is a part of life.