LSD cannot be patented, so Big Pharma cannot make money on it - they'd have to compete on price, which would lead to really slim margins. If LSD is kept illegal, they can sell patented "alternatives" at huge margins.
The medical industry considers the hallucinations recreational LSD users enjoy a nasty side effect. If this wasn't the case, such would possibly be on the market specific known treatments that LSD / psilocybin might help (eg cluster headaches), versus the industry trying to look at similar non-hallucinogenic compounds (eg https://en.wikipedia.org/wiki/2-Bromo-LSD) or other completely different alternatives.
They might find different sorts of chemical structures that are theraputically superior than LSD itself as well, but this stuff wont' happen without minimally having LSD medically legal.
They can still sell the patented "alternatives" : LSD isn't a cure-all and isn't necessarily ideal for everyone. Besides, these patents will eventually run out, so they'll have to think up new ideas nevertheless.
Maybe designated psychedelic theme parks where it's legal and quality controlled with no access to motor vehicles? (with music too?)
Yet alcohol is totally legal.
Like I said I think it should be readily available to those who seek it out, without the threat of substantial punishment, it would just be a shit show if Johny H.S. Senior is able to pick up a sheet at 7-11.
How many "Johny turned the school cafeteria into an acid test" news stories is this LSD legalization experiment gonna last for? It pains me to have to say that because I'd love to be able to pick some up at 7-11, just not sure if it's the best idea.
This doesn't entirely track. Certainly brand-name pharma that do drug research might not be interested, but generic pharma that simply copy drugs from the brands and sell them at steep discounts certainly would.