The price keeps nose diving because there are more sellers than buyers. Why are there more sellers than buyers? Because there hasn't been much positive (if any) news about Bitcoin for most of the year...people are bored.
I think it might be because of federal prosecutors launching a criminal probe into the cryptocurrencies earlier this year, but why?
What prosecutors? What criminal probe? In what country? When you speak in such generalities you don't help us engage in your discussion.