It doesn't have to.  Before Silk Road, there was an early coin mixer on Tor, that I suspect was either morphed into or annexed by Silk Road.  I believe that it may have been the first to call itself The Bitcoin Laundry, iirc, but there have been other mixers that have taken that name since the one on Tor faded away.  I wouldn't be surprised if there are more on Tor that use that name, either.  I don't know this to be true, but when Silk Road first came out, I opened an account to poke around, and was struck by the similarity of the onboard bitcoin mixer to that of the previous mixer I had seen on Tor.  Those similarities may have just been a product of a common intent, or copied sourcecode, but maybe not.

Beyond that, a lot of these businesses were founded by those same early adopters, so it's entirely logical that they would have invested large numbers of their coins into their creations back when those coins were still only worth a nickel apiece.  Many of those early creations have foundation stories that are a bit murky on details.