One of the questions frequently asked on this forum is "How many people have Bronchiectasis, but don't have MAC (NTM)?" The answer seems to be that only an [un]lucky 10% of us have MAC, based on a review of research studies done over the past 15 years.

Credit to @pacathy for this great link:

In reply to @cavlover "I understand that, but it just seems like MAC is so hard to rid. Not going..." + (show)
After I was diagnosed with bronchiectasis and the MAC cultures were negative, I was curious about this, too. While I didn’t find the answer about our chance of getting MAC over our life time, I found a some interesting info.
Here’s one.
https://bmjopen.bmj.com/content/bmjopen/12/8/e055672.full.pdf