A shark does not play with it food, that stupid meme is a stupid meme. Consider the learning exercise, you are born into a sea with no help or guidance, just genetic guidance about likely edible and inedible flavours in the sea you swim in as well as specific trial and error testing method for food sources. So safe trial and error method, be wary, approach target carefully see what it does, hmm, not much. So swing around again and bite, not a too small bite, else target will escape, not a too big because there could be a negative reaction, counter attack or toxic response. The just right bite, which will cripple the target reducing the chance of escape but minimise ingestion of possibly toxic substances or risk of counter attack. Now hang back for a bit and wait to see if minimal blood consumed toxic, takes a few minutes, cant not wait too long else other predators will turn up but need to wait long enough to make sure. Of course that's only the first time that particular target is met, from there on in, easy prey eat at first sight. What makes human difficult initial prey is of course once bitten they seek to immediately get out of the water and they are a vengeful species and do not tolerate eaters of people in any form. Keep in mind, 'missing, presumed drowned', can and often does mean successful shark attack, we only ever really see the failed shark attacks, shark learning about a new potential prey. A successful shark attack you will hear nothing about except a missing person report.