That's the size of a correction in the stock market, it's normal.
Not often. Once every few years maybe, but it doesn't happen once every two weeks like it does in BTC.
Even if there's a correction and then a recovery, BTC's price growth has still been very unusually rapid over the past year, and a lot of it has been pretty rapid. It's worth worrying about for sure.
I agree with this. The velocity of these cycles has been much, much faster than we see in the stock market. The key driver of this is that Bitcoin is participating in a more global market than any single stock. We have exchanges on every continent, it's easy for anyone to buy some, you're not limited by the "share" or "coin" price, you can buy in with almost any denomination of investment (provided it's higher than the fees you'd incur). This makes it easier for people to get in and get out, thus driving the velocity of these cycles.
I also believe we've barely started to realize any sort of adoption. These are still very early days. BUT, we've seen a lot of newbies join this forum this year, there are more newbies on these boards than anyone else! This is an indicator of the increase in interest and ultimately bitcoin adoption.