i think that it is a good investment right now because there are many bitcoins left to mine. But i believe when all of it is Mined it will become more stable and more common to be used as a currency as most of the world will have it. Peole use it as an investment and will for more than 100 years but when it is all mined around 2140s then it will be stable. But maybe we wont be able to see it.