people are being far to self centred about this issue.
for example, lots of people drink at an early age, but hardly anyone goes on to become a full time alcoholic. however, that does not mean alcohol problems do not exist.
the same applies to smoking, drugs, fast food and yes, hardcore porn.
most people will not be affected but its idiotic to suggest that introducing children to extreme material to like hardcore porn is not going to have some sort of negative effect.