I worked in IT, fixing computers. Spent 20 years in the Air Force and I know absolutely nothing about planes, haha.
I didn’t get 100% disability from one specific thing; a whole bunch of smaller things across 20 years of service added up to a 100% rating.
The biggest thing was a PTSD evaluation, which gave me 70% alone. I was in Iraq and saw some shit; nearly died a few times, so that kind of messed me up for a while. I don’t have the stereotypical “go nuts and murder your family in your sleep” kind of PTSD; it’s more just mild anxiety and insomnia that strike randomly. But the military is trying to make up for decades of neglecting PTSD symptoms, so they’re hyper-vigilant about identifying/treating it nowadays, hence the high rating.
On top of that, I broke my leg while serving and it never healed properly, so I’ve had leg pain for the past decade. I barely made it to retirement. I almost got medically separated, but a doctor decided at the last minute that I didn’t need my legs to sit at a desk and do my job, so they put me on a medical waiver and let me finish the last few years of my career. That earned me a pretty decent disability rating as well
Plus I’ve had a few other minor medical issues throughout the years that got small ratings. They have some weird diminishing returns formula for calculating disability ratings, so 20% + 20% ≠ 40%. It’s more like 25%. It’s super hard to earn a 100% rating. I got approved for about 30 independent ratings, which barely made it to the 100% cutoff once added up.