I agree that the current dip probably has more to due around the uncertainty of the China exchange ban situation that it does with Dimon's comments, but everything does have an impact.

I attribute the drop to something like:

China Uncertainty (50%+)
Recent highs that needed correcting (30%)
Dimon comments (10%)
Other factors (10%)

Now bitcoin fall down.so i think it is a little panics for me.

It seems like that most of "this is a bubble" comments come from people with no BTC on hands but really jealous of other success. That said, panic can be good in any ways: it can definitely help to make players more mature

The reason people now are saying that it is a bubble is because the price of this digital currency just blow out to $4000 where it just takes 2 months do double the price. If you will be thinking about it, that is really fast but we are just thinking of this when the price drops and not when it is happening because we are enjoying the fact that we are earning a lot of profit.

I believe bitcoin is a bubble and one day it will burst. That will be a golden time for bitcoin buyers.

They prevent Bitcoin from becoming a true bubble, which would be disastrous. The level of incomprehension regarding Bitcoin is still very high. Jamie Dimon's recent comments show that, like Warren Buffet before him (as of a few months ago anyway), Dimon has no knowledge of how Bitcoin functions as a crowdsourced, decentralized, economical, sustainable, and fast method of immutable data-registration. If these guys don't know, it's a given that lots of recent easy-money chasers don't know either. A friend of mine says his grandfather was taught to drive a Model T by an elderly uncle who sat in the passenger seat with his hand on the emergency brake and yelled Whoa! Whoa! if they went faster than a trot. That's how a lot of people hold their bitcoins. They sit with their hand on the mouse and yell Sell! Sell! at the first hint of trouble. But that's good. Bitcoin can never become a bubble that way because it won't get high enough fast enough. It will slide and even crash from time to time, but since it has real utility (as opposed to tulips --- and the liar loans Dimon's company, J.P. Morgan, was fined $13 billion dollars for selling) Bitcoin will continue to climb after Buffet and Dimon have had uninformed say and momentarily clogged the exits with butts and elbows. As for rumor-mongering China, Bitcoin's Long March will continue there too.

Just sit back and hodl. If you can't hodl here, you are in the wrong game. Try the stock market.