Over the 30 years of investing, I have seen nothing like my investment in bitcoin and other digital currencies. There have been swings of more than 10% a day and I’m up over 100% since first starting investing this summer.

Yet, what might be great as an individual investment would not make sense as a participant-directed 401(k) investment. If private equity/hedge funds aren’t a truly proper 401(k) investment, don’t expect Bitcoin and other forms of digital currency as 401(k) investments as long as they’re volatile and unregulated.