I have had my macaw 51 years. He was a wild-caught adult, so age unknown. I estimate about 55+. My bird hates pellets as well. He used to tolerate the ZuPreem nut-flavored pellets for large birds, but then they discontinued them! The version for small birds was unacceptable to his discriminating palate.

I have tried so many brands and varieties of pellets and he would rather starve than eat them! I figure that he has made it this long on his diet (fruit, veggies, oatmeal, nuts, the occasional bit of egg, etc.), that pellets were just not meant to be.
He is in great health. You would never guess his age by looking at him! My vet agrees with your comment about wild-caught birds having a stronger constitution than captive bred birds. Survival of the fittest!