This question gets asked once a year after a big bull run and a correction. This has happened 6 times now.

9x over 5 days in 2010 from $0.008-$0.08
10x over 5 months in 2010 from $0.08-$1
40x over 2 months in 2011 from $0.07-$30
14x over 3 months in 2013 from $15-$213
12x over 2 months in 2013 from $139-$1132
20x over 7 months in 2018 from $1,000-$19,800
Every time there was a 17x bull run with a 70% correction on average and it will happen again. Source: Complete Bitcoin Price History Chart + Related Events (2009 - 2018)

What is the cause for this?
Emotions. Humans are emotional and herd animals. Only very few people can spot a trend before it happens. 95% of people simply follow trends once the trend is actually up and running.
Legitimacy. Every time there was a bull run, Bitcoin became more and more accepted and legitimate. Then, it became more valuable than it is was actually valuable through point number 1 and then it self-corrected to its actual value.
In the last bull run 5 months ago, lots of legitimate uses and technologies around the blockchain have emerged. However, then they became overvalued, because of point number 1, because only very few companies could actually show real world traction and the market self-correct to what it is now.
Over the next couple of months, these companies will show actual revenue, clients and use, which will cause the next bull run, which will then self correct again.
That’s why, it’s almost impossible that the crypto market completely collapses, because we already have several platforms with real users, generating real revenue. Some examples

Dent, where you can rent your your monthly mobile data with 1 million users
ENJ, a gaming coin that is already being used within Minecraft and soon by its own network of 25 million gamers
Ethereum that is being used by AWS users for dapps
And there are more to come.

So, just hold on to your coins, buy the dip and sell next time you’re at a 10,000% profit. Most traders become greedy when they already made a 10,000% profit and think they can make a 20,000% profit. Once they have made a 20,000% profit, they want to make a 30,000% profit and thus never sell. Then the price drops by 50% and they beat themselves up that they never sold. Then the next time they are at a 10,000% profit they will do the same thing again and not sell.

This is a newbie trader mistake. Don’t be a newbie trader.