>Generally, they will cause extreme anxiety in those who are naturally prone to it, possibly to the breaking point

Generally? No.

I've taken and been around people who have taken mushrooms for over 15 years. I still dabble on occasion. I've never seen or even heard of someone reaching a "breaking point". This is not to say that it can't happen, but saying that mushrooms will do it, generally, must be supported.

That said, mushrooms are no fooling around. If you have no experience with "being high", and the altered mental state that that entails, I would never recommend diving into multi-gram does of 'shrooms. Once you've had some experience, it's much easier to tell yourself, "I'm high, this will pass. Enjoy it."