Thanks LSD?
2001, despite its legendary status, was actually a bit of a flop at first. Its initial release was performing so poorly that MGM was preparing to pull the film from theaters and cut their losses until theater owners insisted that they didn’t.
What MGM hadn’t counted on was drugs. Theater owners noticed that young adults, particularly hippies, were buying tickets in droves to watch the “Star Gate” sequence while extremely under the influence of whatever they could get their hands on. This legitimately helped the film find its audience. So… Good job, drugs.