I don't know where you heard this, but this is a highly dubious assertion.

I know people who have in fact abused ayahuasca, take it compulsively, and have had negative impacts on their life from taking it.

There's a long and sad history of various drugs being claimed to be harmless or even beneficial, only to have it revealed later that they aren't.

Cocaine was such a drug, with Freud being a huge fan of it, claiming it as a miracle cure with no potential for abuse. In fact it was used to treat morphine addiction.

Heroin was also initially used as a treatment for morphine addiction.

The methadone came around, and was used to treat heroin addiction. But, surprise! It turns out that just like heroin and cocaine, methadone itself can be addictive.

Marijuana was widely hyped as completely harmless, but it turns out that some people can get (psychologically) addicted to it, abuse it, and suffer negative effects.

Anything (whether drug, activity, object, or food) that is highly desirable can be abused.