It's still a commodity, at least Bitcoin is. Reading about the other one is interesting. Commodities "investing" is really tricky unless you understand the price drivers. To me, to want to invest in a currency, I'd have to believe that that currency was going to replace the USD as the standard currency for international trade. In spite of the "End of America" video series, I don't see any currency poised to replace the USD any time soon. For a few years, people swore it would be the Euro. For a few years, people thought it might the Yuan. Now, some people are saying it'll be Bitcoin. The problem I see with Bitcoin is that there are literally billions of people throughout the world for whom strictly digital currency is useless and impractical, and I don't think that's going to change in my lifetime.
I share my story of speculation in a company called Ariba back in 2000. Fresh out of college, but yearning to get rich quick, I sunk $1000 into ARBA at around $120/share thinking it would become the way that businesses made transactions between businesses in the future. When I finally sold it, it was worth about $180. If I'd held it through 2012, it would've rebounded to about $300 before the company was sold. I did a similar thing at the same time with a biotech company, with similar results. The first $2000 I invested ended up becoming less than $400 and neither stock recovered after the crashes. That $1600 was my lesson in what can happen when you chase returns, follow hype, and don't understand WTF you're buying. It was speculation which happened to coincide with a market bubble in equities.
I consider myself lucky to have learned that lesson in 2001, because I applied my learning since, made bank by investing intelligently during and after the great recession, essentially treating it as a fire sale on stocks instead of worrying about the value of my portfolio that day, and continue to invest well today. I recognize that my portfolio value could be cut in half again with a similar crash, but I have some non-equity holdings which help alleviate and ride out that kind of volatility. I also have a pretty good idea that my investments will be profitable into the future, even if they look awful tomorrow or the next day.
Plus, as mentioned, stocks pay dividends and rarely stop just because of overall market reactions.