If they were born and raised in captivity their odds of survival are pretty low. Like someone who always lived in a large city and never went camping being dropped off in Alaska odds of survival.

Rehabilitation only helps so much without the actual experience of growing up with other members of their species in the wild.

Edit: Of course the adults in the wild are the ones that survived until adulthood so I still lean towards attempts to rehabilitate and release, just noting it isn't as simple as releasing.