The difficulty with "crypto currency" is that there is not a lot that is like it already. Most systems generally rely on a central issuer that controls it, such as government backed currency, or even private 'currencies' such as air miles points, or credit card points.
With Bitcoin, it is a decentralised network which while operating will continue to issue currency by itself, rewarding those who perform the difficult job of cryptographically signing the blocks.
While air miles have an intrinsic value - you should be able to purchase flights with them as long as the issuer remains solvent; gold has industrial uses - e.g for making electrodes; and currency can be used to purchase anything in a given country; Bitcoin's value is limited - mainly what other people are willing to pay for it. While Bitcoin remains popular, the value should remain high and increase. However, if Bitcoin goes out of fashion, the value could drop to zero.
Perhaps there is some value in that holding a Bitcoin entitles you to use the Bitcoin network to transfer the value of that Bitcoin to someone else in the Bitcoin network, but with the current transaction processing times and fees, it may be easier to use something else to transfer money.
Is Bitcoin an 'Investment'
A Bitcoin is almost the definition of a pure speculation - mainly due to its limited intrinsic value. It's price is purely dependent on what people are willing to buy it at combined with the ever-reducing supply. Perhaps it might be better described as a bet on (or index) of Bitcoin's popularity.
There are many places where you can put money that will actually improve the world. With Bitcoin, you are simply tying up capital, with the hope that someone will be willing to pay more for it later. While this is similar to 'investing' in gold, it is not the same as investing in a company.
When I see the financial media talking about people 'investing' in Bitcoin, it makes me cringe. While technically it could tenuously be regarded as an investment, is it a good investment? Would you invest the same amount in gold... or palladium.. or other exotic precious metals. Bear in mind that these metals have more intrinsic value than Bitcoin.
I hold Bitcoin, have mined some, etc. It is valuable now, but could be less valuable tomorrow. Don't invest if you can't afford to lose the money you put into it.