There is no such thing as a sure investment. Of course, NEM could fail just like BTC could fail or any other cryptocurrency. Cryptocurrency as a whole could fail, even. It's still too early to tell.
What I am always confused about is why people have such a hard time believing that cryptocurrency can have a market cap in the $100 billion+ range. Like I said, Facebook has a market cap of $200 billion and all it does is push ads to people and connect friends/family/acquaintances in a social network. Bitcoin and cryptocurrency are much more revolutionary than Facebook could ever dream to be. Why is it so hard to imagine cryptocurrency having a market cap of $200 billion or more?
Again, the current market cap of all cryptocurrencies combined is $7 billion. That is NOTHING in the world of finance. Peanuts. I know that investing $1000 into something and getting a $1 million or more return on that investment sounds too good to be true, but people don't seem to realize that we are the extremely early investors in this market. If you had given Mark Zuckerberg $1000 to help him get off the ground and start Facebook in exchange for even a small percentage of the company you'd have made millions. Such investments can and do happen. Consider yourself lucky that you have the intelligence and foresight to see that the cryptocurrency market has the potential to become something huge in the years to come.
Simply by being on these forums you are years ahead of the curve. My prediction for cryptocurrency hitting the mainstream and really exploding in terms of valuation is probably around 2020-ish. It's really, really hard to predict with any sort of accuracy though because the Internet can spread information extremely quickly. The world wide web took about 10 to 15 years before it hit what I would call the mainstream, and about 20 years (to present day) before it has reached what I would consider critical mass. I base this on the fact that my rather elderly parents have just now begun to use the Internet on a daily basis at home in the past few months. That's when you know something has really become a part of society for good. These things take time to develop. Your investment in crypto (whether that be NEM, NXT, BTC, or whatever) may not make you into a millionaire overnight, but it most certainly has the potential to make you into a millionaire over the course of the next 5 to 10 years if you play your cards right.
Anyway, that's just my own personal analysis on the matter. This is in no way, shape, or form any kind of investment advice. Cryptocurrency could end up being a complete failure of a social experiment in the years to come. Banks could offer many of the exact same services as cryptocurrency (instant peer-to-peer transfers, no fees, etc.) if they really wanted to. It's not like when you make a bank transfer today that they physically move cash around. It's all digital as it is, but the banks just like to screw us over. The thing is, the banks don't even realize what is happening right underneath them. Just like every other subversive technology that has come before it, cryptocurrency is poised to obliterate the banking system right from underneath its own feet just as we've seen happen in so many other industries over the past decades since technological progress has started accelerating at an exponential pace.
That's why I'm invested in crypto, and particularly NEM because I feel like NEM has the potential to be THE cryptocurrency that brings crypto to the masses over the next few years. Of course, we'll see how it turns out. Exciting times we are living in regardless of the outcome, I have to say.