[svandamme]

as with most WW2 fighter planes, a bunch of them got

shot down
crashed in training
shot down as target drones
sold to allies
lost in Korea as RC flying bombs
sold second hand to private owners
given to museums

the few privatly owned war birds out there, got bought by somebody who typically bought a couple of them, kept 1 and used the others to part out.

I reckon more mustangs ended up in the private ownership because
- slightly more made
- USAF moved to jets faster then the USN (jet's on carriers wasn't as easy)
- Landbased planes probably had an easier maintenance life (no salt, no hard landings)
- USAF could get planes sold a bit easier then the Navy (come pick em up at AFB such and such vs Navy had to offload em, dismantel em at the port ) So Navy probably didn't bother as much and sold more for scrap then for flight.