I understand where you are coming from and agree with 75+% of what you state. Most people who say they have a "bad trip" actually say it was better defined as "difficult" and had long-term benefits. Here is a key statistic from this study:
"Despite these difficulties, it is notable that 84% of respondents reported having benefited from the experience, with 76% reporting increased well-being or life satisfaction attributed to the experience."
Set and setting is important. Do not try psychedelics to solve problems.
But set and setting is not everyting. A bad trip might happen anyway.
Who knows about its genetic, biological and psychological constitution and reaction before the trip ?
That is why a medical expert as trip sitter is so important.