Have you ever stopped to think that half of the Akatsuki was immortal?

• Sasori was a living puppet
• Hidan makes sacrifices and does not die from physical damage
• Kakuzu stole hearts and extended his lifespan
• Zetsu has been hanging out since Kaguya's time
• Orochimaru stole bodies and now he stole Zetsu's, he doesn't need to change anymore

Honorable mention to Nagato who, when inventing the paths of Pain, practically created walking corpses.