The Winklewii's bitcoin ETF SEC filing includes all the dangers of owning bitcoins. The good people of r/buttcoin on Reddit summarized it for you:
http://www.reddit.com/r/Buttcoin/comments/2rv44y/the_winklevoss_sec_filing_is_an_absolute_comedy/
http://www.reddit.com/r/Buttcoin/comments/2rv44y/the_winklevoss_sec_filing_is_an_absolute_comedy/