I don't think anyone sat down and said, "I'm going to create a housing bubble, tank the economy, have people forced out of houses they couldn't afford because of said bubble, and cost millions of people (including myself, with high likelihood) their jobs".

Wall Street has had some very negative effects on the economy, but I don't think those were intended. There wasn't malice. It's just that we, as humans, are terrible at handling complexity beyond certain levels. Take one of those now-infamous mortgage-backed securities. To analyze the thing, you need an economist, a mathematician to model it, a programmer or two to write (and test!) the modelling code, business people who know the involved counterparties and how they will behave under distress-- that is, will our counterparty make good, or default?-- and lawyers (because the damn things are, at the end of the day, contracts). The things are dangerous because no single person on earth holds even half the knowledge to know what the thing is actually worth. But (as in government) that complexity is the product of creep, not (in most cases) intentional malice.