This wasn't my experience at all in 1975. Maybe it was the congregation you were in or who your elders were. I've heard different stories from different people about what they experienced during this time and they are all different, but all I remember is my own personal experience.
The elders and CO in the congregation I grew up in made it quite clear that nobody knew when the end was coming. We were told we had no idea if 1975 meant anything or not. There certainly was a vocal minority who insisted something was going to happen, but those in charge in our halls, and those giving the talks, most of them at least, warned everyone not to speculate. We had so many "its wrong to speculate brothers" talks that I actually remember that more than the whispers about something might happen. Now I certainly remember some people, a minority doing crazy stuff like selling their house or selling their business. But I remember those people were thought of as kooks and it was wrong to be doing what they were doing. And lets face it. There were a lot of not-so-distantly-past hippies who took a lot of drugs right before they became JW's at that time.
I believe through the years what happened in 1975 has become greatly exaggerated. Why? I don't know. I know more people who left the witnesses after the explanation of the overlapping generation concept than 1975 coming and going. As a matter of fact I never knew anyone, and I was part of a big region and big group of congregations, who left the witnesses after 1975.
Everyone's experience is different. Sometimes I think we take our experience as what everyone experienced, because we assume everyone lived the exact same turmoil, emotions, or events. But life and history isn't like that. The truth is what the collective experienced. Not what the individual has.
Just my opinion.