Volatility is bad for bitcoin (the protocol) adoption, even though it doesn't seriously affect it's function as a transfer protocol since there are plenty of ways to convert to other currencies instantly.

Any investment in actual Bitcoins (the coins) is purely speculative, since there is no return unless the price goes up. Speculative investment is still investment, but it not the only way to invest in bitcoin (the protocol), one could put money in a bitcoin startup or service company.