In an economic sense,
An INVESTMENT is the purchase of goods that are not consumed today but are used in the future to create wealth.
In finance
An INVESTMENT is a monetary asset purchased with the idea that the asset will provide income in the future or will later be sold at a higher price for a profit.
I really don't want to turn these into an economics class but the both definition of what investments are clearly should settle the argument of whether BTC is truly an investment or not.
I believe that at this time you should only invest in bitcoin in order to minimize the risk and make the profit the safest, you can see that the market is constantly fluctuating and difficult to guess so you Only bitcoin trading, we can see that altcoin prices have been fluctuating sharply over the last few months and I think altcoin will die in 2018.
I don't that alt coin will be die because of ICO's, they create new coin almost every week that's why it is too hard to get a good coin because too many coin but the demand was still slowly increasing and that is what I see now, the many token we have but the lower number that it take.
Yes, I think it is asset but there's investment involved because you can loose and gain money from this using putting from it and for now, we see that it is full of investment and we cannot see the asset of this coin.