Seen it. I nearly quit in the first minutes, I thought it was going to be just a promotional praise of the "King Robby".
But the movie is much more interesting - and emotional - than that, I'd say a bit like "Bustin' down the door".
I am happy for Robby that we see him evolve during the 5 years of the movie. If he has kept his attitude of "If you are not the best you are not a man" he had at first (and before the reality check of the injuries), he may have had a lot of mental issues coping with aging later on. It would have been interesting to have a discussion with him and Gerry Lopez, with so different ways of thinking...
Kudos to Robby also to show his struggles while learning foiling, most pros will hide always their learning phases (like Robby apparently did for WInd, Kite, and SUP)
I highly recommend reading this interview of the director, quite enlightening:
"I said, "Who's Robby Naish?" Which may have been a sign that I shouldn't do a film, but the more I was totally transparent that I'm not a sports guy"moveablefest.com/joe-berlinger-robby-naish-longest-wave/