Earlier quoted context omitted.
The main point is that it is decentralized and (ostensibly, with enough care) anonymous. This makes it ideal for illegal transactions (drugs, gambling, weapons, contract killing, child pornography). These being incredibly inelastic goods, price fluctuations will do little to hamper continued growth of the Bitcoin.
I dont buy it just like Feds apparently dont buy it either (yet); otherwise they would be already shutting it down. While bitcoins can be used for illegal transactions, it does not mean (and never will) that 99% of transactions will be illegal, just like Feds won't shut down knife factory because some knifes were used to kill. At the end, paying for something illegal is not illegal on its own; its the act or good you…
Did you declare all your bitcoin transactions to the IRS? You may already be in trouble...