Clarke never got round to patenting the idea of a geostationary communications satellite.
Years and years and years ago when it was first reported to me that there were many lascivious moving images on the internet I thought, personally I would prefer to spend hours and hours watching cute furry animals. Maybe, I thought, I could set up a “web site” containing short video excerpts of animals, particularly juveniles, behaving in an appealing manner.
It seems someone else has already done this.
What did you never get round to patenting?