Shrug???
When you stand back 10,000 feet, you can see that world-wide, any city large enough to feature on any reasonable map of the world's top 250 cities is going to have a crunched housing market.
A reason for this is that these cities have all become global destinations.
Think of AirBNB - they could certainly have entries for Sedro Wooley Washington, or for Bellingham Washington, but they'll definitely have search and presence in Seattle Washington. Seattle and Shoreline aren't that different and some of the nearby cities are honestly pretty similar to Seattle nowadays -- Bellevue, Everett, Tacoma, Olympia, Kent, etc. So what "Seattle" is - to many people - is a pin on a map. A place where their business is headquartered etc, or where they think they live and work. If a Law Office wants a bit more of a state-wide, regional, or international office, it would HQ in Seattle. Now all the workers there think "I work in Seattle" and "I should live in Seattle then my commute would be shorter" and instantly you have vast competition for living space here.
It's the same all over the country, all over the world. Major cities are where people think they work (very few people literally work dead center on the official center of any city, they are always somewhere near it - a bit north, a bit south, etc depending on geography). People have some level of commute time they'll deal with to go to and from home and work and that sets up suburbs since the mega cities might not be where they're finding good schools for kids.
In some ways, I kind of wish that cities did have a limiter on growth, making some of the excessive growth automatically go elsewhere.
But what can you do, LA the city is not really as large as the entire Valley of sprawl. I'm sure I could look up LA's population and be surprised about how small it is, but the greater LA area probably has a multiple of the main cities population.
Next, these big name cities are investment opportunties world wide for people that don't want just their home countries' stock in their portfolio. Sometimes they would just like another place to go to that they own personally. I think the US and Canada are both attractive markets because you're not leasing the land from the State - you own it - in perpetuity and you can pass it along to your heirs (if you pay taxes on it and don't get it reclaimed or foreclosed). It's like an international bank account without some of the hassles of that. People eagerly sell their luxury apartments to foreigners with cash and that's not honestly a bad thing.