In the spirit of the original post I thought I'd share a bit of my personal experience with crypto for those interested.
I've been doing the Mustachian method of index funds, slow-and-steady, etc. for 20 years. It has served me well. I kept a couple percent of my money reserved in cash for opportunities and then put a small percentage of that money into active investing (we're talking at most $2000 or so) mainly for entertainment. Trading individual stocks got me more active in something I enjoy so I played with it in a low-risk manner for a while. Good, wholesome, nerdy fun.
I learned about Bitcoin back when it was around $200 or so and bought $5 worth on a paper wallet from a friend. I just wanted to know how the technology worked, really. I set it aside and then learned more, bought a little more, etc. I went to a Crypto conference in August, 2014 and listened to a very compelling talk given by Vitalik Buterin about this new thing he was building called Ethereum and I immediately saw potential - if he and the team were able to pull it off, of course.
I put a few hundred dollars worth of my speculative "play" investment money into it and promptly forgot about it for a year and a half or so. I didn't even realize that people were trading it in any serious way until I looked up Ethereum and my $0.30 Ethers were trading at over $1 each. Crazy ROI especially for something so speculative. It went up so fast after that that I didn't know what to do. I sold enough to recoup my investment and to realize a little profit and let the rest ride. It was all safe money now.
Fast forward to a few months ago and what was left had gone up to be worth hundreds of thousands of dollars. It went from "price of a new car" to "price of a decent house" so quickly that I was gobsmacked. My wife and I decided to get out while the getting was great and realized enough gains to pay off our house! We're in our late 30s and there's enough left to buy another house with... all from a speculative bet 3 years ago.
I don't want to get anyone's hopes up nor do I want to proclaim that I'm some kind of investing genius. I won the lottery and I know it. This was a once in a lifetime speculation done entirely with money that was outside of our normal investment plan. Had I lost the few hundred dollars, fine - not a huge setback.
As to current holdings, I remain fascinated by the space. I hold Ethereum (inside and outside of an IRA), a little Bitcoin inside an IRA, and a few smaller startups (LINK, QTUM, NEO, MTH, OMG) that I managed to purchase at their ICO or close to it. Some are up, some are down. I doubt that I'll strike oil again like I did with ETH though.
Now I'm trying to reconcile just how far out of whack my overall asset allocation is. I never intended for crypto to be such a large portion of my portfolio and I'm trying to slowly divest. The tax situation is such that I want to do it slowly because of the capital gains. Come January 1st I'll be liquidating some more and moving it into good 'ol VTSAX. :)