system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did psychedelic drugs get popular during the 60s?

Who started this trend? Was it just rock bands taking it that caused this movement?
gpt
A huge cultural revolution caused by a variety of social effects happened to coincide with the advent of LSD by Swiss chemist Albert Hofmann and the proliferation of it by Harvard professor Timothy Leary and American bands like The Grateful Dead. Initially, the movement was spearheaded by clinical trials within medical circles and academia. LSD was primarily restricted to these circles throughout most of the 60s but began to "leak out" as the 70s drew nearer. The "leaking out" was created by many of the academics and medical professionals who sought to proliferate the drug as a spiritual mission. The Vietnam War and the Nixon era created incredible social tension between genders, races, classes, and generations for which there was no clear path of mitigation. This perfect storm created a youth backlash against the statu quo which was largely characterized by an isolation/"fuck your values" type of movement rather than the more nuanced "let's sit and align our values" type of movement. Not without good reason, IMO. 

There was just a whole lot of uncertainty, and LSD and music had a grand opportunity to offer an escape. 

I recommend looking up Albert Hofmann, Timothy Leary, and The Grateful Dead. These forces mixed with Nixon, the Vietnam War created the revolt.

EDIT: Awfully pathetic that the only valid answer is getting downvoted while "oh because it's cool" is at the top.