Why is New Jersey so expensive to live in?
You will immediately recognize that I am by no mean an expert economist, but I think the reason can be expressed very simply. New Jersey is the most densely populated state in the Union.
More people per sq. mile = more consumers chasing fewer services per capita + greater (more costly) infrastructure needs (including "hard" infrastructure like bridges, roads, and schools to "soft" infrastructure like teachers, police, and firefighters) = higher cost of living.
Because the government takes so much money from the people and intrudes into so many aspects of the economy.
The Democratic People's Republic Of New Jersey is simulataneously an oppressive state and an expensive one for productive people.