I don't think this was an issue of public perception/respect in society in general (although I would have to go back and read SS).
Rather, I believe DB himself thinks that a "gambler" (one willing to take risks) is better than a "rounder," which I think he uses more in the terms of what we might call a "grinder" today. In other words, a rounder is a leather-ass conservative rock, not a risk taker, but someone just grinding out a living without motivation for moving up in stakes.