News stories about this footage of a shark swimming near humans seem to assume the people are woefully unaware of the tooth-puppy sidling up to them. A man casually starts to wade to shore, apparently unperturbed by the shark. While it's certainly possible he missed the huge shark right in front of him, he could also just know you've got to keep your chill around a shark. Yes, you should get to shore and away from the shark, but try to do it without wriggling around like live bait.
Icthyologist (fishologist) George H. Burgess of the University of Florida Museum of Natural History has a few tips to avoid becoming sea giblets. One of them is "don't splash around like a dumb B-movie victim," which I'm paraphrasing. Apparently, "erratic" movements can attract sharks. I initially read this as, "erotic movements can attract sharks," and I thought, well, yeah, no duh.
Fortunately, the man in the video was moving neither erratically nor erotically, and the shark left him alone. Either he lucked out and didn't notice the shark, or didn't want to become a movie trope and calmly walked to shore instead of splashing around like a coked-up eel. There are a few other fun tips that Burgess suggests to avoid getting tooth-tickled by a shark: