[confounded]

The whole idea relies on a hierarchy of power so unnerving it's the basis of folklore across human cultures.

Unlike costmetic surgery, your gain depends on someone else's loss.

There are likely to be supply/demand issues in a society with where citizens have free access to each others blood for recreational purposes.

[Tenoke]

>Unlike costmetic surgery, your gain depends on someone else's loss.

How? The 'loss' from donating blood is fairly minimal. If properly compensated everyone could be coming out better off.