Its also possible to work out when its going to crash, because nothing should double in value within days - that is just stupid!
When it does that, you need to sell a little of your investment so that you get some profit.
Within a week or so, it will drop in value by about 30%, and that price will almost be stable and will last for a month or two, before it all starts to go nuts again.
This run-up started at around $70. This entire time people predicted adjustments (why I stay away from the speculation board). Many predicted a far greater run up than occurred-- some predictions topping $3,000.
The catalyst this time around was the Chinese news, and nobody could have predicted that.
Your broad statement "Within a week or so, it will drop in value by about 30%" is completely unsupported by history. In fact, if you followed your advice you would have sold around $650-- or hell, $350 or less.
I'm sure there is money to be made in trading-- but even including this weekend's
adjustment, Bitcoin is up 705% in the last 6 months. Simplistic "sell when it goes up" strategies don't apply.
I agree completely with your last piece of advice.