What do you disagree with? That quality of life for doctors will need to drop for M4A to be effectively implemented, or that doctor shouldn't be making 6x what teachers make? Would it be ok for doctors to make 2x what professors make? $200K instead of $300K?
People shouldn't become doctors to get rich, and they will 100% oppose an M4A plan that constrains their pay. But the doctor lobby shouldn't have veto power over what type of healthcare we have. The question is, which option is better for society: doctors having the highest occupational salary + poor people having no/shytty healthcare OR doctors reducing their salary to be in line with their international counterparts + everyone having quality healthcare. If the prime imperative is for America to be a place where doctors can get rich, then the former option makes sense. But if the prime imperative is for America to be a place where everyone gets access to quality healthcare, regardless of their station in life, then the latter option makes sense.
And if doctors are as magnanimous as you say, and people don't go into medicine to get rich, then there shouldn't be pushback from doctors to the latter option.
None of this precludes going after the other sources of bloat in healthcare. In fact, bringing down doctor costs won't solve this alone. But I don't see how this gets solved without doing so. And I wouldn't call teachers or professors or government lawyers low skilled, those are all professions that require post-secondary schooling, some as much as doctors. And I think people in those professions have a right to question why they're subsidizing the doctor's 3rd vacation or country cottage with their taxes, and why the doctor is making 3-5x as much as them. As other countries have shown, that disparity is not some intrinsic, essential facet of practicing medicine.