As things are now (and as GP points out) speculation is probably the right word, not investment. From Wikipedia [1]:
Speculation is the practice of engaging in risky financial transactions in an attempt to profit from short or medium term fluctuations in the market value of a tradable good such as a financial instrument, rather than attempting to profit from the underlying financial attributes embodied in the instrument such as capital gains, interest, or dividends.
Bitcoin is speculation. Not only is it speculation, but it's the kind of speculation where you can fail for reasons beyond your control and which no one knew existed. (See transaction malleability, which hit the reincarnation of Silk Road pretty hard.)
Losing your coins to theft or third party loss is simply spirit shattering, and unless people are truly okay with their coins literally vanishing, I would hold off on converting a sizable portion of your wealth into coin. It's easy to say that you'd be okay with losing it all, but the reality of it is much harder to deal with.
I've been thankful to have experienced the highs and lows of bitcoin -- it's been a tumultuous introduction to the internal psychology of investing. The key to my bitcoin-related happiness was to never play with more than I could afford to lose. If the price goes to zero today, I'll still be thankful for the many lessons I've learned.