Yes. In a simple form. A rising XBT:USD price attracts more users. New users bid up the price, attracting even more new users. This has happened several times since 2010, resulting in large new waves of users each time.
That's is just a simple speculative demand for bitcoin. Applicable to most investments.
Bitcoin's integration with credit markets should allow for a new form of reflexivity. A smaller number of users can now use leverage to control a disproportionately large amount of bitcoin. Borrowing money to buy bitcoin will increase the value of bitcoin, which will allow bitcoin holders to borrow even more bitcoin. This reflexive phenomenon has been largely absent from previous bitcoin bubbles (although Bitfinex allowed a small amount of lending in November 2013 and a few people borrowed against their cars and houses).
Bitcoin market capital is very small relative to wall street players. They probably don't need to borrow to speculate, and there are many other vehicles to do so. They can speculate on the success of bitcoin with their share holdings in bitcoin startups. They can speculate by shorting corporations which bitcoin can "kill".
It should be very interesting to see how this enhanced reflexivity from credit markets on exchanges will influence the next bull market.
Yes, what I would like to see is derivatives to allow investors to cover bitcoin on the downtrend. It may sound pessimistic, I believe it's a beneficial investment tool to reduce the volatility of Bitcoin.