The current wave is certainly going to crash at some point. Just looking at the list of coinmarketcap currencies, almost every single one in the top 200 have seen double digit or better percentage growth. The problem is that many of these altcoins offer nothing unique or innovative to the world of cryptocurrencies. Because of that I can only assume that much of the growth is due to wild speculation being driven by pump and dumps.

That's not to say that the interest and growth in cryptocurrencies is completely false. There really are a number of new and exciting ideas (such as steem) that are picking up steam (heh, get it?). Bitcoin will hold steady when the drop comes, as will Ethereum and a handful of other popular coins. But I foresee a big drop in the rest. Long term however I would expect the innovative ideas to continue growing, even if there is a drop in the short term. Those that stick with it and don't get scared off will be rewarded.

As for advising others, I would tell them to diversify. Its almost impossible to know which ones will emerge as the real deal, so if you're going to invest do so with a number of choices. Don't put all of your eggs in one basket.