This is where pseudoscience comes from. You dropped acid and think it helped you but you probably tried many different things before acid which "didn't work". In all likelihood the acid had nothing to do with it; it was just a coincidence that your symptoms improved.
Also, it's common to have a lot of migraines for a period in your life and then stop having them. Or sometimes the reverse. I used to get very painful migraines about twice a year. Eventually that stopped. I still get migraines a couple times a year but they're quick "silent migraines" i.e. not painful, just annoying and disorienting.
Possibly, but there are a lot of people that self-administer LSD for migraines who say it helps tremendously. I'm also one of those people. Between occasional LSD and daily magnesium supplementation, my migraines are very infrequent these days.
Are you aware of the ample research and scientific knowledge on the interplay between the 5-HT2A receptor and inflammation, vasomotor effects, and effects of 5-HT2A activation on migraine and cluster headaches?
This is also how many scientific discoveries start. An n=1 observation. Then more observations, then more validation. This is how we ended up getting ketamine for depression.
I disagree, if it stopped it stopped. It could be from something else, but his LSD intake is the most likely candidate. It would become pseudoscience if he or she would claim that this will work for everyone.
Also, don't forget that science can make a similar flaw. Just because a drug works on average, doesn't mean that it will work for you or that it won't have any negative side effects. Human variation can be quite big with certain things.
Also, it's common to have a lot of migraines for a period in your life and then stop having them. Or sometimes the reverse. I used to get very painful migraines about twice a year. Eventually that stopped. I still get migraines a couple times a year but they're quick "silent migraines" i.e. not painful, just annoying and disorienting.