My first ever beardie was a rescue from a friend who didn't want him anymore, so just decided to stop feeding him
FOR 2 WEEKS he had no food or water, lived in dusty sand, had no supplements, and received no attention. I aggressively scolded him and immediately took the poor guy when he casually mentioned the lizard one day. He was about 1 when I got him, so he was definitely messed up from then on. Kinks in the tail, sideways fingers and wrists, underbite jaw, and couldn't lift himself very well. After food, a vet visit, and fixing everything I could husbandry-wise, he lived to be 10! And he was definitely my sweetest beardie and would love to be carried around.
Rescues are hard though, because even if you try your best, they sometimes just can't come back from issues. I had rescued another after my first passed away, and she was SO amazing. Such a sassy personality. I'm not sure how old she was, I only had her for 1.5 years. She had been a school pet in which stupid kids fed her terrible things like Cheetos, and her lights were so far up, she barely got the temps and UV she needed (she was in a tall thin aquarium on sand). She was thin but still full of energy when I got her, and she became plump and happy. But then she got parasites somehow, and no matter now aggressive I was with them, they were just as aggressive with her body. I had to give her shots and all kinds of meds, but the whole ordeal was just too hard on her.
The rescue I have now is 7, we've had her for 4 years, and she came from a reptile pet store that some kid's mom dropped him off, saying they didn't want her anymore. She was SO skinny and so sad looking, we had to take her. Hopefully she lives to be an old-timer just like my first. I do pamper and fuss over my little ones, so maybe that helps longevity?
It's really impossible to know how long they'll live, what with genetics, past husbandry, unknown/unseen issues etc. but it's a blessing to love on them and give them the best environment you can. Reptiles are professionals at keeping sicknesses and issues a secret as long possible until it's almost too late to act on. It's so important to do as much research as you can and have the best husbandry possible, so they can live long and happy lives! <3