[neilk]

Well, these people are wrong. Anxiety is very common on any kind of marijuana. I've had that before too, so my sympathies.

You can have a bad trip with pretty much anything. Bad trips on psilocybin are common, especially if you don't have anyone to help you redirect your mind to a better place. However, unlike pot anxiety, even the bad trips often seem valuable in retrospect.

I personally know of one person for whom the trip didn't end on schedule. She had to stay at her mom's place for a few days while she emailed dozens of poems to her friends about how much she loved them. But as far as I know she's "normal" now. You can find cases of LSD-induced depression as well, just Google it. Some apologists try to claim these cases are just "unmasking a problem that was there already", but that is cold comfort for someone who gets it. So no, it's not 100% safe.