With Apple, there's intrinsic value to consider. And frankly, if you sold enough Apple stock for it to go down 50%, I'd personally start buying. I doubt that's the case for ETH, where there's only early adopters buying it hoping to strike it rich.
Costs about 16% APR to borrow ETH for shorting on Bitfinex right now. So if you're expecting a >=90% crash in the next ~5 years you'd still make a profit.
So I don't really see your point by comparing it to Apple as it's not the same at all. It's not equivalent to cash or public stocks but that doesn't mean it's not a worthy investment to make for someone interested in the technology or potential in Ethereum.
What the currency needs is something of tangible value underpinning it and this project seems like a good way to add real value to back up the currency. It could potentially result in some successful businesses and projects which would compensate early adopters at a higher level both in the value of ETH and in dividends.
But I don't believe there is any doubt that this is speculative. I visited /r/ethereum the other day and someone asked why they backed DAO and a common reply was "I wanted to support this new technology as much as seeing it as a possible investment opportunity for financial return".
It's high-risk speculative investments but also a group of people who are interested in the idea itself and are willing to invest money at a potential loss in the process. Just like any startup founder.
That's where the pyramid/ponzi/bubble comparison comes in. There's no actual value (yet?); the adopters would have to keep buying more to keep the price up and to keep the "value" of their holdings high. Not because it's so useful; just financial incentives.
That's a logical fallacy. As a Ponzi scheme is not the only way, nor the best way, to add value to the investment. So I don't think that fairly represents the market incentives that exist for the early adopters. Especially given the context of it's creation and the community of early adopters around it.
As I mentioned in my comment above, they are incentivized to have the project produce real tangible value if a) they are interested in seeing the technology succeed and b) they want returns on investment via dividends, which is typically the premise of a longer-term investment.
Even if a percentage of investors don't fit that criteria, I highly doubt they represent the majority. It would only require is a sufficient enough sized majority of well-intentioned investors to keep the project operational.
I'm not convinced the only way it could generate returns - and more generally prevent a drop in value - is by continually adding more investors. I expect they will put in some real effort to make it work as a functioning economic entity.
Actually, more was sold during this period. In just the last 24 hours on Poloniex, the volume was 20 million USD.