system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Greece is on the brink of leaving the Euro so why is everyone withdrawing their money from ATMs?
gpt
To understand this you need to understand how a Greek exit from the Euro ("grexit") would work.

Greece would order all its banks to close, and to turn off all their ATMs.  They would stay closed for a few days, maybe a long weekend.

During that time, everyone with a bank account would be informed that any balance they had in Euros will now be an equal balance in Drachmas.  The Greek government will keep the Euros (what few there are; there are not enough to pay everyone anyway), and they can print as many Drachmas as they need.   They may also try to go after Greek citizens with foreign bank accounts.

As soon as the banks reopen, people will begin trading Euros for Drachmas and vice versa, just like people trade any two currencies, and the market will establish an exchange rate, as it does for other currencies.

However, even though the government gave everyone 1 Drachma per Euro, once the exchange rate stabilizes, 1 Drachma is going to be worth much less than one Euro.

If you take your money out of the bank and keep it in cash, it will be sheltered from that massive loss of value.