But I think the shares are worth around 5BTC and while I wouldn't buy them at 10BTC (I cannot afford to at that price) I'm sure some people can. It's a good place to put your Bitcoins and it's better than leaving it in cold storage or hot wallet. You might have to deal with the fluctuations but if it gets to 5BTC it's not going back down to 4.5 so the problem of fluctuations mostly affects people who get in too late. If you're getting in at 5+ then I would think it's far more risky than getting in right now at 4.5.
Emphasis mine, and I agree with the points in bold. To extend it another step, getting in at 4.5 is riskier than if you'd done so at 4.
If you bought in at a lower price (let's say <2 for the sake of the discussion), the question is not whether you lost or gained money, but how much profit you've made.
I disagree with your statement that share price won't drop to 4.5 once it passes 5; all I can see are those "hold, spartans!" memes on /r/Bitcoin when
BTC/USD was $200+. If x can go up, x can go down, which leads me to your statement that AM is a better parking spot than cold storage; that's only true if AM shares don't decrease in value.
There is no reason to move the Bitcoins because there is nothing else paying dividends this much. So where else will people put their savings? You keep it in a cold storage and it doesn't collect 20-30% APR. And there is really nothing to spend it on except BFL and we see where that goes.
For the next month dividends will be high and there is no better investment. In August we can look at the share price then but I suspect it could be over 6 or even over 7 by then and the pressure will exist to sell but will that be enough to out pace demand? If the price of Bitcoins keep dropping then I would say no. The cheaper Bitcoins are the more demand there will be for these particular shares.