This sounds terrible, but when industries really boom (in the US at least), it's largely because I-bankers have figured out how to chop up and sell unprofitable

This sounds terrible, but when industries really boom (in the US at least), it's largely because I-bankers have figured out how to chop up and sell unprofitable businesses to people at home watching CNBC. See, for instance, internet entrepreneurship, 1997-2001, construction, 2005-2008. That being said, I say Green/Energy.