Usability. Tell it to the masses that this wonderful digital payment is only good between 2 private person but they can't use it for paying at Amazon (the ultimate goal) or any other online retailers or not even at the coffeehouse and see how the value and usability declines. Also, if they get fucked by not delivering goods or services, the authorities will just say: it is illegal anyway. So its value is directly tied to usability and security.... There is really no point in arguing about this....Not to mention that right now the widest use of bitcoin is investment/speculation and once it is illegal most of the players will drop it like a hot potato...
The only way feds could really damage it any further is if the feds go as far as trying to setup stings where they put guys on the street that want to transact bitcoins with them and then if you transact with an agent you get busted. Like if you sell drugs to a undercover cop. Even so, people still buy and sell drugs every day. They can't stop drugs with the war on drugs, they can't stop bitcoin. They can only make it more difficult. It's like if the feds made gold illegal. They will have to pry it from a lot of peoples cold dead hands. Like I said, the idea of bitcoin is brilliant. It's just hard to get your hands on for the majority of people not willing to go through the hassle. It would be the same if gold were against the law, hassle to get.
They won't care that much. Once it is illegal and no vendor is going to touch it, why would they care if a few 1000s people use it in private transactions? Hell, you could use Monopoly money with your friends, as long as everyone accepts it, the Feds still don't care. Once your Monopoly money start to COMPETE with the dollar (which is by the way already illegal), the will notice and take action. And since there are already 2 existing laws* against bitcoins, they don't even need to change the law, they just have to start to enforce it. *I offer 1 BTC as a price for anyone correctly identifying these laws. Nah, just kidding, I don't have any bitcoins, but I give a loud applause...
Well, during FDR's administration gold was made illegal and it put a real crimp in new gold purchases by much of the public. I'm not suggesting players didn't buy through foreign accounts etc. The fact is they can take 80% (or more) of the markey away on most financial products through legislation. As I pointed out earlier in this thread it is all well and good to talk about how impotent they are but they can make life quite unpleasent if they choose to. Drugs are always the wrong example. Financial products, as a well know manufacture of securities taught me decadersago, are sold not bought. Drugs are just the opposite. The good customers search out the seller with high quality merchandise.
A parallel with BTC usage after a ban is the black market in USD or DEM during the cold war in iron curtain countries. Using anything except the local funny money in places like czechoslovakia was illegal but everyone did it anyway because it was almost impossible to enforce. You could walk into a store and be offered two prices depending on if you were using a hard currency like USD or the local commie fiat.
They used it because there was advantage in using it, not because it was hard to get caught. If there is not much advantage for the general public for using bitcoin (but there are quite a few disadvantages), they might as well just use dollars or pesos. What the faithful don't get is how easy it is to outlaw bitcoin, and why would any decent and popular vendor risk using it once it is illegal? Again, if you want to use it between private parties, go ahead, just don't cry when one side screws the other. No currency likes competition, so the US dollar isn't unique in this regard. If selfmade digital currencies started to take over the Euro, they would be outlawed overnight... Right now bitcoin still exist in a quasi legal state because it has been flying relative low under the radar. Just wait until there is a famous kidnapping where they demand payment in bitcoins (criminal activity) or there is a Arab sleeper cell discovered in the US heartland who got their funding via bitcoin (terrorism) and that will be the end of bitcoin... Mark my word....
I agree there's not much advantage right now for Joe Sixpack to use BTC. An unprecedented financial crisis could provide the catalyst to get more of the general population involved. The Cyprus banking crisis caused a sudden spike in demand for BTC. It wasn't due to speculators but scared people trying to buy BTC any way they could as a hedge against fiat risk. An interesting speculative question is what would have happened if BTC had been around leading up to the 2008 finanical crisis. BTC only came into existence in 2009.
I prefer the idea of a city coinage. You could even have ones made out of gold, silver, platinum etc. so they have value elswhere. What would Detroit's be made out of ? rusty old iron maybe.
I have never owned a bitcoin and until the CME accepts it as margin I probably will not buy even one. That said, my guess is the US Treasury or the Department of Justice will not get stiffed by them.