You are way overthinking this. There is no such thing as an opposite edge. LOL. If there were, like you said, it would simply be an edge. A trader either has an edge or they don't. If they don't, their expected return is random. They are equally like to make money then not. Emotions have nothing to do with it. I mentioned Vegas because they really like guys like you who mistake randomness for edge. They have built very nice hotels off the backs of guys who confuse the two hence why I said they would appreciate your visit.
There are no guys who blow up consistently. There are guys who are undercapitalized. There are guys who are over leveraged. But that has nothing to do with edge. Yes, there are guys with $300 FX accounts who blow through that in a day using 50 to 1 leverage. But in reality, if I backed that guy "secretly" with 100k, I would not risk my 100k next to his $300. I would have a 100k account positioned to make a mere $300 or less then 1% on his blowup. I could just as easily lose $300 and he would be celebrating that he doubled his account. There is no way to normalize the risk.
I use to run a prop firm office in Chicago where pretty much everyone blew out. But not because they had "negative edge" but because they churned their account to zero between commissions and the bid-offer spread.