And very, very few of them die.
This seems counter-intuitive in a way. We read and hear about airline disasters, and they are utterly horrific. In a moment, hundreds of people are gone. I think this resonates in our memories so strongly, because we can imagine ourselves in their places: locked into a metal tube in the sky, utterly helpless as it falls to the ground.
With that said, you are literally in far more danger getting into a car for a quick trip to the store, or stepping into a water slicked shower, or going for a walk just as a thunderstorm is about to hit. And probably, most of those things don't scare you at all. And there are good reasons for that, just as there are reasons you are afraid of flight.
We humans have evolved to fear certain dangerous things: gravity is a pretty major threat. If you fall from a high place, there isn't much you can do to prevent injury and death. Thus, the humans more afraid of heights and falling have done a better job of avoiding such things, and thereby have done a better job of surviving and passing on their height fearing genes.
And it doesn't get higher than miles in the air, really.
That said, you're safer up there than in a car. Why? Well, automation and redundancy. Most planes at this point functionally fly themselves. Not only that, but they have two "drivers" at minimum in most case. you can't say that when taking a car somewhere. That, and a multitude of regulations that drivers would reject on the basis of "freedom" (freedom to drive irresponsibly, really,) have the skyways far far safer than the roadways overall.
So, overall I would advise you to enjoy your flight, right down to the adrenaline rush as you are about the land. It is all a part of the fun.
As for California...lovely country. Enjoy it, and try to ignore the potential for devastating earthquakes...