You pay zero for housing, zero for medical for an entire family...not even a co-pay. After 20 years you get a pension for life. And for many, they are doing it for reasons other than to put more money into a CxO's pocket.
In my day job, I work with enlisted (not Air Force) and a bunch of ex-military, so I'm pretty familiar with the situation. I have actually been wondering if military retirement drives down wages, because a bunch of guys take pretty low salaries that are only okay because of their retirement check. Great deal for them, and definitely well-earned - it's no cakewalk to earn military retirement, harder than anything almost anyone in the private sector has to do - but I wonder how it works out across the labor market.
I do feel like, outside of the officer corps (who for some reason seem to hold onto it more often), the sense of noble purpose often gets crushed out by the inanity and bureaucracy so many of them have to put up with. IME that's usually why they don't re-enlist.