Will also add, not sure how big of a difference it makes, but the data in that article also captures the window of time when Mass implemented its millionaire tax. There was a lot of blustering from the 1% about moving out of state and taking the jobs with them; I doubt the last part but wouldn't be surprised if a good chunk ended up leaving for elsewhere to avoid paying.

Also worth looking at how the transition to remote work is a contributing factor. Since the pandemic, it's no longer necessary for a lot of people who used to work in Boston to live around Boston, and so they can keep their high-paying jobs while moving to more affordable surrounding states (or even other parts of the country). That is definitely middle-upper class migration and it affected regions with high percentages of pre-pandemic office jobs the most, which applies significantly to Boston.

That being said, I know anecdotally many members of my generation here in Mass (80's-90's Millennials) still live with their parents well into their 30's, and those who did not have that as an option often resorted to moving out of state. Rent remains high and property is even higher, so it's a waiting game to see if/when this bubble pops. Mass also happens to be close to the bottom in the US in fertility rate (which is not an inherently terrible thing) but speaks to the difficulty of starting a family here.

I guess the medical care is just so good here that the old people aren't dying off fast enough!