“I remain skeptical.”
Probably wise to do that both ways - don’t unquestioningly accept that Marijuana and THC are absolutely harmless as a matter of faith either.
They induce clear cognitive and personality effects, as well as producing well known changes to the brain and neurotransmitter levels over time.
Intermittent, moderate use will cause no problem for most people, and is effective for stress and several medical conditions (like nausea, PTSD, anxiety, short term depression, seizures). Marijuana (and THC) is an effective drug, and a pretty safe one - but not entirely safe. Not for chronic long term use, and not for people suffering from psychosis or schizophrenia.
Know your risks.
Straw man and moving the goalposts - I have never claimed that marijuana or any other substance is harmless.