As someone in finance/banking, I brushed off cryptocurrency for a long time. Fortunately, I actually took the time to understand it before the latest craze and have seen a 500% increase in my investments. People don't understand that it's so much more than a currency. Really it's more about the technology behind all this.
Bitcoin is Xanga, Litecoin is Myspace, Ripple is Facebook. Mark my words, Ripple will change the world, with or without coinbase. As someone who works in banking, I don't think people understand how big of a game changer Ripple/XRP is. Not only that, but it has traction, great marketing and is aiming at being legislatable. It is MUCH further along than any other cryptocurrency as far as real world adoption goes.
Ethereum is like Microsoft, and I think it will be huge for smart contracts over the next 3 years. Ada is Apple. It will ultimately be a much, much better Ethereum.
Stellar is full of sour grapes of those who left Ripple for ideological reasons, but are now doing the same exact thing with Stellar. It still might do well, but go with Ripple.
DO NOT BUY TETHER. Or at least, don't keep your money there long. It's a scam coin. If/once it get's exposed it will go to zero.
Lastly, it's fine not to invest. It's true the cryptocurrency market is highly volatile. It's true that prices could plummet. Whatever you do though, don't discount this, I truly believe cryptocurrency is here to stay and will change the world for the better, with or without the non-believers.