1. Large capital flowing in, can just as easily be pulled, causing even more volatility on a larger scale.
2. Institutional investors have huge capital reserves to manipulate the price.
3. Most bitcoins will change hands from the long-term hoarders and early adopters, to the filthy rich Hedge funds.
4. The price might increase so much, that the smaller investors will be priced out of the market.
5. A very high price and high volatility will change Bitcoin's use from a Commodity/Currency to a full blown Commodity.
What other negative side affects of the Bitcoin ETFs, can you think of, or are you just another speculator that wants to make a huge profit from Bitcoin?
We should care more about the impact that this might have on Bitcoin as a driver of innovation and a alternative payment option.