Once your nsec is stolen, you can never recover it for your exclusive use, that's correct. Once it's lost, you can never recover it for any use, that's also correct. But same is true for bitcoin keys, and yet we're hoping to build the world around it, and people build tools to mitigate these risks. Nostr key != Bitcoin key, but there are much more similarities than differences. Here is more on this: nostr:nevent1qqs0qkyxmykx2a5f98e88c2ayyz44z53h8ntvqp0fusge4r62m9m7mcql9f4x