To answer your question directly: Right now, Bitcoin's movement seems to be determined by influx of dollars by rich people who are trying to "invest" substantial sums in it.
That is always a worry. This money is leaving the system, not being loaned out and can cause deflationary cycle if a lot of rich people do it.
Unfortunately, Bitcoin is also hard to confiscate (unlike gold, which was confiscated for similar reasons in 1933 - to inject liquidity into the system).
So I can totally see this as a valid strategy for rich people who want to take their money out of the system.
Personally, though, I'd advocate Bitcoin as a currency equivalent, but not as an investment.