As far as this latest bear market from the 18th, I think that it was about people deciding to switch their coin holdings over to Bitcoin Cash; the news broke yesterday that Bitcoin Cash mining would be more profitable than Bitcoin mining, though with lower transaction fees and less stability of course. If you look at the graph for Bitcoin Cash, it's spiked dramatically, somewhere around 100% increase since yesterday - about the same dollar amount that the 10% drop in Bitcoin price correlates to. That doesn't mean that Bitcoin Cash will now take over, or that Bitcoin is going to stop growing altogether, but it's possible that we're entering into a more sideways/bearish market for a while.
Personally, I bought Bitcoin around the time the OP started this thread, while everyone else was panicking over the split; that's given me 100% ROI in a month's time, so I did sell half my stake during the slide yesterday, though still higher than Bitcoin has settled at right now. I'm actually rather annoyed about the timing of the slide, since I had decided to sell on the 17th when it broke $4500 and took a day getting my coins transferred over from my paper wallets. Oh well. At this point I'm entirely playing with the house's money, so I'm certainly not going to panic over losing what I never had.
I am still bullish on Bitcoin in the long-term. I just think the current, short-term bull run, which started when the news hit that SegWit was locked in at 80%, is running out of momentum and has stalled for the time being on the news that Bitcoin Cash is better than Bitcoin in any sense, even if not better overall. It may only be stalled for a week or two, at the rate we've been going, or it may stall for months as the reality sets in that Bitcoin still has some uncertainty in the future. SegWit developers and Core are not at peace over the NY agreement, last I heard, and there's a possibility of yet another hard fork. Who knows whether people will panic over it, or look at it as another opportunity like the last one turned out to be? The last one was only an opportunity for people who took Warren Buffett's famous advice, "be greedy when others are afraid, but only when others are afraid." If everyone looks at a fork as an opportunity and it ends up causing technical disruptions, it'd most likely trigger a crash and panic sell. The market is a funny thing sometimes, given that it's just made up of lots of people. If any one of you tells me that people always make sense, I'd like your personal information so that I can have you committed, because that doesn't make any sense and you'd clearly be insane.