Blood replenishes though. It's not really a body part in that way, just like hair. (I don't know if regular donation has any long-term effects?) In that sense (no permanent impact) I'd see a greater problem with poverty driving people into working as miners or soldiers, than as blood donors.

Semantics aside, the real problem is the (desperation of) poverty, not the results of it.

Blood is not really a body part in the way most people think of it. It’s much closer to saliva in that it’s generated by the body and used up fairly quickly. Red blood cells for example live for around 120 days which is limited because they don’t have DNA.

I suspect this is an adaptation to both increase hemoglobin transport, but also to reduce cancer risks.

The human body suffers just as much from wear and tear like anything else, maybe even more so due to being just a bunch of flesh/bones that can't be easily replaced.

In that context, anybody who works hard labor is trading in part of their health for income because many labor-intensive jobs will take their toll on the body [0]. Up to a point where people either have to switch line of work or go into early retirement, as certain parts of their body stop functioning properly and they are stuck with chronic pains for the remainder of their lives.

[0] https://www.reuters.com/article/us-health-work-occupational-...