Hippies like to associate with things that are exotic. Buddhism used to be exotic and there were too few educated Buddhists to tell the hippies off properly, so for quite a while hippies with all their horse sh!t explanations of why it's okay to do the stupid things they do in the context of Buddhism, ran the scene and were the face of Buddhism.
Most hippies didn't follow Buddhism in a mature way, but it's possible that a few people got their start with Buddhism when they were hippies and later practiced Buddhism in a more mature way when they were older.
It's hard to say for sure, but I think that the immature interest that hippies had in Buddhism was better than having no interest at all. Even a tiny bit of Dharma can bring many benefits.
The past 40 years has been the equivalent of a retarded kid pretending he is an astronaut.
Maybe, but still hippies who believe in love and tolerance are less "retarded" from a Buddhist point of view than unethical, but well-educated world leaders are.
I guess this brings us to another confluence between Buddhism and hippie ideology, and that is left-wing politics.
It would be quite hard for a Buddhist to argue that the government should cut spending on education, social services, and healthcare and should instead give more tax breaks to large corporations and should fight more wars abroad and should be more racist. All the compassion teachings of Buddhism inevitably pull someone at least a little bit to the left. Most Buddhists aren't saying, "Buddha bless the USA! Let's kick out all the foreign immigrants! Let's bomb another Middle Eastern country who irritates us!"
The real astronauts being thoroughly offended when people compared them to the retard but at the same time not sure what to do about it. I mean, hippies are retarded, whaddya gonna do?
But some of those astronauts used to fly planes in the air force and dropped bombs on lots of people, and that certainly isn't cool or good from a Buddhist perspective. For example, Buzz Aldrin flew 66 combat missions in the Korean War.