Strictly speaking, speculation is a genuine investment strategy, but it's only appropriate for those with a high risk tolerance.
But the point is defining investment so widely as to include this sort of behavior just devalues the term.
I have no doubt that bitcoin is a good investment in the long run.
Except several vendors have recently started dropping it as a currency primarily because a currency which is deflationary makes a good investment and a terrible currency. Bitcoin has no use-case, or maybe you can disillusion me and tell me what you've done other than hold it?
Besides, what this thread has illustrated to me is that bitcoin is a gamble, same as a penny stock.
1. Takes some of the commodity off the market, saving it for the later spike in demand.
2. Promotes more aggressive investment now to hopefully provide more supply later.
Those benefits offer grounding for the speculation. You can do some calculations to see how well those things might pay off, and make a bid based on that imperfect information.
I don't see how that applies very well to any pure "store of value" like a cryptocurrency. How big the spike in demand will be has no bound on the error.
Maybe when cryptocurrencies become a medium of exchange it would make more sense.
This should be contrasted with 'speculation', which best applies to short-term strategy that merely seeks to skim alpha off the top of fluctuations in value, without regard to long-term health of the instrument.