If you've invested lots of money in Bitcoin and it's price has dropped, the situation can appear to be pretty bleak; but being aware of a few things can avoid regrets later on:
Most altcoins tend to be tied to Bitcoin's price, so when Bitcoin crashes most altcoins will too. Some will crash further than Bitcoin percentage-wise and some won't.
Look through some altcoins you believe in, and if they've crashed harder than Bitcoin, consider buying some of them with your Bitcoin. Although the fiat value of Bitcoin may be lower, you might be able to get a good deal on some altcoins.
Avoid buying any fiat-based items with your Bitcoin. For example reinvesting on cloud mining websites, buying items online, etc. As the fiat value of your Bitcoin is lower during a crash you you'll have less buying power, so the best bet is to either cash out if you can't risk further losses, or to 'HODL' until its value goes back up.
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