You're putting way too much emphasis on all these things. Sadly this is something that tricks many people (including you apparently)... the reality is, nobody can predict the markets, even if they have a PhD from Harvard.Did you go Harvard?
Anyone who pretends they can is a fool, and should be exposed as that.
Besides, economics (and market finance) fields are quite new, and pseudo scientific to begin with. This field is full of people who apply flaky pseudo science and pretend they know what's going on. Markets cannot be precisely modelled. They are full of uncertainty because they are based on human behaviours, emotions, and culture.
If someone confidently says they know what the market is going to do in the coming years, and says it's backed by scientific analysis, they are a fool.
Roubini is a fool and a clown. As @Jimmy pointed out, this guy has been frequently wrong. And that's the case for all of these characters who wave their PhDs around to try convincing people that they know how to outsmart markets.