There is little quantitative data on the side effects of MAC antibiotic treatment because 1) the population of patients and treating doctors is widely dispersed, 2) there is no routine mechanism in our country for reporting side effects from medications, especially in the case of multi-drug therapies and 3) if you ask any practitioner, there are many "silent sufferers" and "silent quitters" when it comes to taking medications. There have undoubtedly been small scale studies, which you can probably find with some diligent research. I often look to reports from the NIH as a starting point.

Here is what the Cleveland Clinic has to say about life expectancy with cavitary MAC, with or without treatment, "Approximately 1 in 4 people with weakened immune systems who develop the cavitary type of MAC lung disease die within five years of the initial MAC lung disease diagnosis. Earlier detection and treatment drastically minimize the long term risks. (https://my.clevelandclinic.org/health/diseases/22256-mac-lung-disease)

And here is what they have to say about IPF, "Some people live only months after a pulmonary fibrosis diagnosis. Others live several years. Many factors affect your prognosis. Even your provider can’t predict some of these factors." And the American Lung Association says, " When you do your research, you may see average survival is between three to five years. This number is an average. There are patients who live less than three years after diagnosis, and others who live much longer."

If the MAC is treated, it will help preserve your remaining lung tissue longer, hence giving you more good time... and the decision to treat MAC is not irreversible. If the pulmonologist recommends antibiotics, you can try and see how you tolerate them. If they are too tough on your body, you can always stop them.

So it seems you are in a spot where some really hard decisions need to be made. Are you seeing a pulmonologist you can talk with? Do you have someone who can accompany you to appointments and serve as your recorder, so you can have good notes to review later?
Sue