Never been to California, don't hate it, but don't exactly have a super high opinion of it as an outsider either. My personal reasons are

Much of the state has had a water crisis to one degree or another for most of the last century. That seems like a pretty clear sign that the environment can't really sustain the amount of people and industry it has, and yet we keep at it.

A lot of the state is prone to earthquakes, wildfires, mudslides, and other crazy shit. Again, seems like a less than ideal place to live.

The climate really isn't for me, I personally like cold winters with snow, that's not really a thing in a lot of California.

I'm from the northeast, I happen to like the overall vibe of people from this part of the country, west coasters have a different vibe, not necessarily a bad one, but it's not one I want to surround myself with full-time. Some (but not all) people get really snooty about the East vs West Coast thing, and while it definitely goes both ways, and I'm certainly biased because my experience is pretty much entirely from the east coast perspective. It seems to me like when that happens west coasters activity dislike the east, whereas the east is more indifferent towards the west.

Politically I overall tend to agree with the trends in CA in broad strokes, but it feels like they go weirdly overboard in some things (like the prop 65 warnings) and take weird half-measures in other. That's not a unique California problem, but because they're such a political and economic powerhouse their missteps have bigger ripple effects than most other states. I think overall most of the country could stand for our laws and policies to be more California-like, but we shouldn't be holding California up as some sort of gold standard to copy exactly, and I think that's a distinction that is lost on some people.

It's also expensive.