Every decade has its own unique goofiness- the '40s had zoot suits, and the frontal lobotomy as a treatment for depression, the '80s had Boy George, but I think one decade in the 20th century sticks out for embracing crazy ideas. This is not a matter of political leanings, or taste; this is about a nation actually treating seriously a bunch of ideas that in retrospect were too weird even for satire.
The younger readers may not believe me. For proof, I'll list some (warning, some of these ideas still have adherents, like the Japanese soldiers stranded on the Pacific Islands to keep fighting for The Greater Asian Cooperative Sphere)-
1. Biorhythms - This was a popular theory that every person has cycles of efficiencies in their life, and at some times you are more creative, or strong, or focused, than at other times. There were actually biorhythm centers in major cities that would quiz entrants, and then produce sine wave charts (for a fee) to show them when they were most and least productive. Many athletes used these charts for training and competition planning.
By the '80s, you had to go to game arcades to get a biorhythm chart, between Space Invaders and the change machine. The theory does not even have enough adherents to defend it on Wikipedia.
2. Ancient Astronauts - This idea was most closely associated with the writer Erik Von Daniken. His theory was that the ancients could never have produced the works they did - the pyramids, cities, roads, calendars, etc. (this may be based on his personal observation that he had no idea how to make any of those things), so "somebody" must have helped them. The ancient artifacts representing mythological gods are, per Von Daniken, actually showing aliens from outer space, their exagerrated forms not primitive abstract representations, but instead astronaut suits!
"Must be astronauts!"
Want to play a fun game? Ask yourself one of the questions Von Daniken felt that it took ancient astronauts to solve- like how would you make the pyramids' tiers almost perfectly level, without modern laser levelling tools? If you can answer that (it's not that hard), you are qualified to be an overseer of the guys pulling the blocks up the pyramid, and not one of the pullers.
3. Talking to plants - This idea posited that talking to plants helped them grow. The appeal of this idea is that, maybe all of life shares a common plane of consciousness, and we all need each other, man. Although thoroughly debunked, this practice is still widespread, having moved from theory to custom, and on its way to superstition.
4. EST - You younger readers are not going to believe this one. EST (Erhard Standard Training) was the motivational seminar from hell. Werner Erhard (not the birthname of this native mid-westerner, always a warning sign about the guy you're going to have speak to your employees) devised this multi-day performance enhancing system, characterized mainly by his disallowal of bathroom breaks.
There you have it. These movements were far more popular and accepted than you would believe. I cannot think of another decade that rivals it (the competing ideologies of National Socialism and Communism in the '30s required a similar credulity, but was more tragic than comic). Growing up in a decade so receptive to ideas like these gave a lot of boomers the idea that the world was an interesting, curious, and gullible place. Other '70s icons, like earth shoes and The Starland Vocal Band are starting to make more sense now, right?