You can know how to trade, have the perfect risk management but something can still go wrong in the end regardless.
The 2015 flash crash destroyed retail accounts, even for the profitable traders. You cant predict when the next flash crash will happen can you? It was so bad that some brokers went bankrupt. The price movement was so quick that stop losses weren't triggered, or were filled at ridiculous prices which exceeded the amount held in some accounts.
The point is, anything can happen at anytime. There is nothing we can do about it other than to completely stop trading.
Just to add, not knowing how to trade can increase the risk of blowing up a account. The risk of blowing up a account is already there (even just by having money in a FX account can be risky), but not knowing how to trade can increase the likely hood of the account being blown.
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