It would be useful to allow more organ trading in general, not just in blood or blood plasma.
Iran is one of the few countries that allow you to pay eg kidney donors. Guess who doesn't have a waitlist for donor kidneys?
Iran is one of the few countries that allow you to pay eg kidney donors. Guess who doesn't have a waitlist for donor kidneys?
And a poor person with one kidney less but extra health checkups can probably get better health outcomes than a poor person with two kidneys but extra health checkups. (This assumes that the kidney sale comes with some mandatory regular health checkups. Just like kidney donations do.)
In Iran, there is no tracking of donors and most donors don't want to be associated with the donation long-term, as it's connected to their poverty and the shame of their poverty. In the limited surveys that have been done many also noted that they haven't been properly informed about the risks of a donation.
Donation of blood and other replenishables is a bit different of course, but allowing open sale opens some bad avenues in terms of people effectively being forced to (which could carry risks they wouldn't normally want to take).
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[1] Well, not practically…
Your two statements contradict each other.
In any case, we only have a finite number of days allotted to us on earth.
> [...] you can't donate a second time [...]
You can't repeat your 30s either.