I mean, realistically.. a lot of people never leave where they grow up, so a lot of people just think of CA as home. It's been this way pretty much for a long time.. so it's more of a slowly boiling pot I suppose. People are escaping at record rates though, so I feel like we may be getting to a tipping point soon.
The weather is VERY nice in a lot of areas. Low of 50, high of 100, usually around 75 and sunny at any point during the year. You can drive to surf, sand, snow within a couple hours most times of the year. You can make a LOT of money here. Things COST a lot too, but if you've grown up here, have a family house/etc it's clearly not completely unaffordable. There are also cheap areas of CA.. but they're not very nice at all.
Being close to Hollywood is also a draw for some people I would assume. If your goal is to 'make it big' your chances are better here than anywhere else, as with anything else in life, it's usually WHO you know not what you know.
Floods aren't a huge thing thanks to no rain, fires suck, but they don't happen where most people live, and earthquakes are so few and far between I don't even think they should really be considered. Sure, a big one could come and fuck shit up.. but the last one I recall doing anything like that was Northridge in.. 1994? 26 years ago! Hurricanes and tornadoes are a yearly affair, so I'd be more afeared of those personally.