Except as they add infrastructure and upgrade existing roads, utilities, etc, they also add long term upkeep costs. When the oil goes away and people leave you'

Except as they add infrastructure and upgrade existing roads, utilities, etc, they also add long term upkeep costs. When the oil goes away and people leave you're left with roads and sewers to maintain, people to lay off at Wal-Mart and McDonalds and lots of empty housing to depress real estate prices. That's why boom cycles seem so often to be followed by serious bust, because boom creates long term costs.