The "Lehman grandma" has become a household word of the great financial crisis.
This meant senior citizens who had been sold Lehman certificates by their banks and savings banks - financial products that are often difficult or impossible to understand for laypeople and which in some cases resulted in high losses in the wake of the insolvency of the Lehman Brothers investment bank.
In some cases, embarrassing court processes afterwards showed that the certificates could never have resulted in profits for investors even without the bank's insolvency.
Last but not least, the stories of the Lehman grandmothers have severely damaged trust in the banks.
The hype about cryptocurrencies like Bitcoin and Ethereum brings back memories of the time before the financial crisis.
Digital currencies can certainly play an important role in the future.
For the moment, however, the following applies: very few people should understand what exactly is being traded there (something with data packets in the blockchain).
The market is not regulated a bit.
And although steep price gains are often followed by steep falls, many want to be there.
Anyone who is currently trading in crypto currencies has to put in some effort and should be aware of the risks.
But if the banks and savings banks now want to open up crypto trading to the general public, they and the supervisory authorities should make sure that the customers know what they are doing.
The Lehman grannies shouldn't be followed by the crypto grannies.