That really has mostly to do with the high cost of living. And it's going to be high in an area inhabited by businesses on the cutting edge of technology. Those jobs have high wages because they need highly educated people, and highly educated people come from the best universities in the country, many of which are in Boston, and Cambridge. Not to mention the great schools in commuter range in Providence and Worcester.

Red states don't have higher education, and they don't have innovative industry, so they don't have the population density issues that blue states have.

Maybe if red states had these things, they'd have a high cost of living, too.

Most of the people fleeing MA for those states are working remotely for their companies still in MA. Mostly DINKS and young (primarily male) single professionals that don't really have public education or healthcare as any sort of immediate concern. That's gonna lead to problems when the average age of red state populations inverts itself. Better make sure that they can't not have babies.