People regularly perform backups of their mind. In the 
  case of death or injury or illness, a new body is grown 
  and their backup is restored into a new body.

...

  and their backup is restored into a new body.

Well, yeah, of course you'd want that. Because it's just SO reassuring to know that even if you die, an identical twin can pick up where you left off.

What a relief, to know that something that looks like you, can keep listening to your favorite bands, wearing your clothes, eating the same favorite foods, and having the same opinions about the world after you die.

Me? If I had a brain back-up, and they could grow a copy of my body in a vat... Why, I'd just run around fighting lions with my bare hands, and wrestling hungry sharks in the ocean. Who cares if I get completely eaten and digested?

The new copy can pick up where I left off, and just beat up whichever animal ate me!

I don't care about my duplicate. I only care about whether my current consciousness continues. I don't think so highly of myself that there needs to be duplicates running around. Maybe Elon Musk or Ray Kurzweil feel differently.

Still if you get knocked unconscious or even sleep who's to say if that's the current consciousness or a new copy.

One of Kurzweil's projects is he wants to resurrect his dad because he misses him. Making copies kind of makes more sense if they interact with others rather than a brain in a vat type scenario.

That's what you think. Duplicates are expensive. Same as if you drove carelessly and wrecked your car because you could just get a new one :)