I think there's going to be a big adjustment in 2018.
Just like there have been big adjustments in every other year. Bitcoin is unstable, but
until this very second has only been going up on average.
So I expect to see us smash through $10k perhaps even $11k or $12k followed by a big fall, maybe down to $2k if past performance is any guide.
Bitcoin has dropped that much in the past, for instance 2013 and earlier, but has matured a lot since then. I realize it's very risky to say "it's different now", but it is! Mt.Gox manipulation caused a huge uptrend followed by a hard crash. The recent very big attack from Bitcoin Cash only had a "small" ($2000 drop) and short (it was higher again in just days!) effect.
There are more than 150 billion dollars invested in bitcoin right now, when the price was $1000, there were less than 15 billion, it means that there was much less people than now, and of course, less money in here.
This isn't how market cap works: a market cap of X doesn't mean X has been invested.
The 24h volume is $4B now, while the market cap went up $9B in this time. And those $4B includes sales too, it's not just new dollars flowing in.