I've heard such numbers before and asked my doctor about them, but been told that those are overexaggerated. A higher risk apply to patients with intestinal diseases such as Chron's (not me) or when doctors have conducted minor surgery from inside the gut.

A normal colon is quite flexible, and should not get hurt just from the endoscope being pushed through the gut.

Snipping a "normal" polyp or taking a biopsy would cause a little bleeding, but should heal up quickly. I've been told that I could see blood in my stool after it, but it's been so little that I haven't.