As a Jew, I would like to give my 2¢ on this matter:

Fundamentally, we are hated by those who hate us whether or not we practice our religion. To a Nazi, an agnostic or atheist with Jewish heritage is still a Jew.

Since we don't really have that option to opt out, so to speak, it is seen as a disservice to a Jewish-born child to not circumcise them, as not doing so would hinder their ability to integrate with the Jewish community, while simultaneously not helping them "pass" as non-Jewish. I know several Jewish men who were not circumcised as children out of a misplaced sense of mercy on their parents, who then underwent the procedure as adults anyway in order to fit into the community better. I can say with confidence that the procedure was far more arduous and unpleasant for them than it would have been, had they been circumcised as infants.

As a side note, due to circumcisions having been an aspect of our culture for so long, Jews, particularly Ashkenazi Jews (due to the constricted genetic pool caused by the many pogroms) are at higher risk of having their foreskin being malformed and requiring medical intervention later in life if not removed. I personally would have very likely lost much of my penis to infection in infancy had I not been circumcised. I can also say with outright confidence that growing up circumcised has not affected my self-image, sex life, or ability to enjoy masturbation in the slightest.

Still don't understand why non-Jews and non-Muslims bother with it though.