any time up until lift off he could have closed the throttle and aborted the takeoff and stopped.
Very true. Perhaps I'll say that a successful takeoff was doomed...
I Such a pity he started his takeoff roll from the point he did and did not backtrack to give himself a greater stretch of water.
Yeah, not knowing the layout of the lake, he could have been as far back as practical. It would be reasonable to assume that the video was shot by a person standing on a dock. Water pilots are correctly sensitive to blasting/splashing/annoying people on shore, and going closer to an unknown shore increases the risk of hitting bottom. There are many variables, some of which we cannot know. It nearly looks as though had he continued straight out over the coloured sail, he might have made it. But, still, a poor judgement takeoff. For circular takeoffs I have done, I have prethought several abort points. I don't know enough about the Icon to know how it handles circular takeoffs. Sponsons, as opposed to wing tip floats probably allow a little more risk of dipping a wingtip. I can touch a wingtip float near takeoff speed without a problem, but touching a wingtip would be a whole different matter! There's a lot of centrifugal effect to throw the top of the plane toward the outside of the circle, so there has to be lots of aileron effectiveness to oppose that (and a wing tip float is nice too, just in case!)