On 98% of the days that you could have purchased Bitcoin you would have realized an increase in purchasing power in a year's time. In those 2% of cases where you could have purchased Bitcoin and seen a loss over one year, you would have still seen an increase in purchasing power in another 300 days. (This is mostly dealing with the June 2011 bubble)
There has never been a time where you could hold Bitcoin for 2 years and lose purchasing power. On the contrary, holding Bitcoin brings on average a 5x per year return in purchasing power.
Past performance, future gains, blah blah. Judgement is about taking into consideration the facts we have now and comparing them against past performance. There are very good reasons why Bitcoin is valued around $6billion now and very good reasons to think it will be valued higher in the future.
You should be placing your life savings in Bitcoin, and only purchasing the USD that you require and holding it for as short of a period as possible. This would have been the best strategy for 98% of 1 year periods over the last five years, and 100% of 2 year periods over the last 5 years.
Debit cards that draw on Bitcoin balances and allow you to use the VISA and Mastercard networks should be the most interesting products -- because they allow you to expose yourself to the dollar's periodic collapse against Bitcoin for the shortest period of time.
I'm sure I'll be downvoted and that people will tell you that Bitcoin is super risky and that you should only invest what you can afford to lose -- but shouldn't that be the case for the dollar and not Bitcoin?
The dollar loses 90% of its purchasing power against Bitcoin on semi-regular schedules, and people keep purchasing more after each collapse. This routine should get old after a while, but that's what happens when you don't use Bitcoin as your unit of account!