I wasn't around yet when the waterbed craze died!
When I first heard of them I thought they were a joke.
Dad explained that they had been around for while but that they got real popular from the mid 1970s into the early 1980s.
And in fact there was a store on the old main drag where he grew up that sold only waterbed and their supplies and related items.
He apparently never knew anyone who had one.
I am told that one of the big problems was weight load on the foundations of many houses and most garden-style apartments
So no, I've never actually seen one!