First at all let\'s define what crash actually mean. It is a situation with the specific cryptocurrency when demand is decreasing to the bottom level, when demand is decreasing price is falling down too and the value of people\'s assets drop down dramatically. Between two or more cryptocurrencies there can be positive and negative correlation, which means that the price of first currency can change price of the second currency. Bitcoin was the first cryptocurrency ever and for now have higher adoption rate. This factors mentioned and many others factors could mean that every other cryptocurrencies are connected to the Bitcoin, so we can not even imagine what impact on the market will completely crash of the Bitcoin have.
In a short period of time, this could be devastating effect for all the people who own Bitcoin, the demand for the coin will dramatically fall down, supply will rise extremely and price of course will fell down. As we already said in the text above every currency is connected to the Bitcoin so crash of the number one cryptocurrency can also lead to decreasing price and adoption rate of all the cryptocurrencies as well.
These days price of the Bitcoin is rising extremely and people are using this increasing to make some profit with day trading or they just bought some Bitcoin at the lower price and now they are selling it, basically the main purpose of the Bitcoin is forgotten and that is regular payment method. Bitcoin is greatest cryptocurrency today so crash of its market would actually means that the market will stop growing and people will start using Bitcoin for its main purpose, for the transactions.
There are some prediction which are saying that Bitcoin would not be able for using as everyday payment method due to high transaction time, so the market could once again become oriented to the value transfer and all others features that blockchain technology and concept of Bitcoin itself are offering to the users.