Great whites are drawn to food sources. Seals have not been culled so herds are at record numbers. Shark are not too smart and occasionally mistake humans for seals.
They are not picky eaters, despite what the they-won’t-eat-you crew says.
Sea Lion populations in Southern California are not at record numbers due to two years of El Niño conditions seriously affecting the food chain starting with the kelp forests. The warmer than normal water over the past two years brought about an increase in sting ray populations and bottom animals are thought to be the main menu of juvenile Great Whites.
There is and has never been "culling" of either seals or sea lions in California - that is ridiculous and you'd be doing serious prison time for killing marine mammals here. Sharks are not stupid and they are not "mistaking" swimmers for sea lions. They are however quite curious and target of opportunity feeders. They have no moral qualms apparently when it comes to finding out if something might be good to eat. If you're unlucky enough to be in the wrong place at the wrong time - - - prayers for the poor gal who was bitten at SanO.
As Pelham noted, sharks don’t mistake people for food, they just rarely encounter people in the water is all. If they do, they will eat you.