No — piles (haemorrhoids) are usually not dangerous or life-threatening, though they can be painful and disruptive. The Association of Coloproctology of Great Britain & Ireland states that piles can often be troublesome and need treatment but are almost never life-threatening. The NHS notes they often improve within a few days with self-care such as fibre, fluids, and avoiding straining.
Still take rectal bleeding seriously: it is often from piles, but it can also signal another condition, so persistent or new bleeding should be checked. Go to A&E or call emergency services for nonstop bleeding, large clots, or severe pain; seek urgent GP/NHS 111 help for high fever, feeling very unwell, or pus leaking from piles.
Source: NHS — Piles (haemorrhoids); also ACPGBI.