BTC is an Over the Counter Credit Swap Derivative (OCD) in the eyes of the law. You can't regulate it without stepping on some very very TBTF bankstering toes.
A bitcoin is an Over the Counter (OTC) Credit-Swap (funded Credit Default Swap or fCDS).
To you, it is only worth what the last guy sold it to you for and made off with. You funded "his" credit for it and the next guy (is assumed to be willing to) fund yours! It is a funded credit derivative backed by nothing but faith.(in a "next guy")
http://en.wikipedia.org/wiki/Commodity_Futures_Modernization_Act_of_2000The reason Bitcoins/Altcoin tokens are legal is because they are OTC derivatives. Otherwise they would be a Ponzi scheme.
https://bitcointalk.org/index.php?topic=175708.msg1832923#msg1832923