You know, I've been thinking about this for a while: on the one hand the logic of the advantage that insider knowledge brings is undeniable. That said, one thing about Cohen, it's clear from his past that the guy is very competitive, needs-to-win A type personality: for example playing poker in high-school the night before his SAT test...
I think odds are that reality is a bit more nuanced than we'd like to think: he is probably a mix of a trader who has a great sense of when to fold his trades and when to press them. Throw in 'edge' and you've got a 'grey' reality (neither black nor white): he did have skill in making the most of the opportunities that came his way, and if these same opps were given to someone else, they likely would not have capitalized anywhere close to what Cohen did. So it's very hard to not give him partial credit for his success.
That said, I still think that today, with 'edge' gone the way of the dodo, it is significantly harder if not impossible to make the same kinds of returns even with the aforementioned skills... I think the odds of him generating eye-popping returns by pure trading skill are a longshot, but hey, maybe he will prove people wrong (who now mostly see him as a washed up insider trader). We'll see what 2018 returns are like. From what I've heard, not so hot...