Ebay and CL aren't guilty of racketeering, because they didn't create their services to sell contraband and evade legal authorities. They both work to keep illegal activities from dominating their business. Clearly, the difference here is intent. SilkRoad was created from the start to be a black market site.
The various federal agencies that are engaging in parallel construction are conspiring to break the law, so yes, they are probably guilty. I wish you the best of luck in getting them arrested and tried.
The bankers involved in default credit swaps are probably guilty of fraud, not racketeering, as they seem to have been deceiving investors about the risk they were taking in purchasing risky loans. I haven't heard any evidence that there was conspiracy to systematically defraud the country, but rather, a bunch of independent players that all arrived at the conclusion that lying about risk was profitable.
Sort of moot, as either set of charges should be enough to start handing out several hundred year sentences to those involved.