I'm not liquidating my retirement fund in favor of bit coin just yet, but as my purchasing power shrinks over time it might be something worth thinking about. It is just too new to put all of my eggs into one basket just yet.
If your purchasing power is shrinking you're doing it wrong. It has been the best stock market in the last 5 years and almost a challenge to not compound faster than inflation..
This will not continue to be the case as QE has influenced returns greatly. This would also not apply to you if you were to able to invest additional amounts into the market over the last 5 years (or large amounts as a percentage of your total portfolio). If you are decades into your career then you would hopefully have a substantial retirement fund saved as of 5 years ago, so the new money that you contribute will do well but the rest would not as a lot of the returns would simply be recovering the losses from the bear market