LSD was new and trendy in certain circles in the late 40s. Cary Grant was tripping at the shrink's and extolled the experience. Plus, there was a taste for trippy shit even before that. Check out the 1943 movie The Gang's All Here if you don't believe me.
I believe you. LSD was promoted as a legitimate form of therapy for awhile there and it certainly had some potential. [Suppressing urge to launch into healthcare and politics rant.]