You can always test out this hypothesis by doing a tab of LSD from the same batch twice while controlling for your headspace. One day, you do it with a positive headspace, and another day you do it with a negative one. If you had a great experience the first time and a bad experience the second time, clearly the headspace alignment made the difference.
Yes, this kind of testing isn't as rigorous as it would have been for a legitimate scientific trial (which I bet we will see in the future as the research into the area accelerates), but imo it is more than just a No True Scotsman backed by broscience.
And of course, no one says that a negative headspace is the only reason for someone to have a bad experience, there are others for sure. For example, certain people with predisposition for schizophrenia probably should abstain as well. AFAIK psychedelics won't cause a schizophrenia in an otherwise healthy person, but I heard it might kick off an early onset if you were going to get a schizophrenia in a few years without any psychedelics anyways.
Everyone knows what it means, and it is way shorter than what I have in the quotes. Pretending it isn't a legitimate word (despite it having an actual entry in the dictionary) doesn't make you look more impressive.
One of the first times we did LSD with my friends in college, in the end we all were thinking "this is why they call it a trip. we all went somewhere together and came back".
Set and setting matter a lot and it isn't bro-science. You're talking about drugs that take your mental chatter and external stimuli and allow them to flow freely. Anything bad or anxiety producing will get amplified and without the proper experience, it might spiral out of control.
Everyone says this and it's little more than bro science. So if you have a bad experience from the drugs, it was because you weren't in a positive headspace? Sounds like No True Scotsman.