I know that. The problem is that people won't stop to think about that. People are used to these papers that they can hold in their hands. "Money" for them are these physical things, and when they give those things to people in their day-to-day trades, they are not used to getting them back. The only exception is when they are dealing with banks. Banks are few, banks are honest, banks give papers back (statements) and everybody else goes to these banks. This is what most people know about "currency" (a.k.a "money"). [You work? You get money. You buy things? You give money.]

How are you going to introduce Bitcoin to them? Are you going to say "I gave my money in exchange for bitcoins"? Sorry, you lost. "What are these 'bitcoins' you are talking about? Can you bring a few here so I can see them? And... what did you say? You GAVE your money to somebody? Are you crazy? Who did you give it to? You are such a fool..."

People don't care about PGP, encryption, SSL, public/private keys, advanced math and all that mumbo-jumbo. It's science fiction to them. It sounds like a fairy-tale.