I think that cannbis most definalty has the potential to create mental illness in a sensitive individual, but I think it all mostly depends on an indivduals mental histoys of theiir family, the stress they may be under at work/school etc etc, what they want to achieve from the drug because some people take drugs to escape from there problems or from reality, and some might take drugs to relax after a hard day at work etc etc. In the end its just like alchol I think (whcih can also cause pycsosis in sustained amounts) as some people just drink alchol every weekend or whatever and it doesn't affect there lives in a partticully negative way , they can have a normal job , support themselves etc etc, while other people coulld become alcholics and lose whatever job or money they may have, so basically I think it depends hugely on the individual as to wherver pycotic symptons are baught from under the surface in an indivudal taking cannbis.