No that's not stupid. It adds a layer of friction for criminals. In Italy where this law already applies for 5000€ (before it was 2000) it helps reduce black market.

Source: I used to be paid in cash (illegally) and it was a pain in the ass to do anything so now I get paid lawfully and my boss pays taxes

Money can be changed into something that isn't money, yet functionally works the same for a single transaction, very easily

Shops usually don't accept "something that isn't money" as payment.

This measure aims to make it harder for criminals to wash their illicit money using legit businesses.

Under the new rules, businesses and professionals selling goods or services will no longer be allowed to accept or make cash payments of €10,000 or more.

This doesn't apply to private transactions, by the way.
Off the top of my head, I can't think of a single example of a legitimate legal business that would be done using cash in that amount.
So while there's definitely a danger of the rules being tightened over time, this specific change here doesn't raise my concern too much.
What bothers me more is the utter lack of any effective measure against the true problem in tax fraud – those who do it at a truly large scale still get away without any punishment or control, and in fact sit at the table when the tax laws are written.

10,000 pounds

The UK is not part of the EU.

Margarita machines dont pay for themselves.

https://www.forbes.com/sites/instituteforjustice/2025/09/26/forfeiture-funds-encourage-law-enforcement-to-misspend-public-money/

Yea i love when most police raids for suspicion of drug dealing end up being something along the lines of "we broke into this person house and he had one half smoked joint and 10,000 dollars in bills" which of course means that the money is now proof of crime and belongs to the cops now

The limit only make some illegal payments (like under the table payments) only a little more inconvenient, it does not prevent them.

Bad, because running all payments through banking system is a systemic safety risk.

If banking gets paralyzed like in Greece during debt crisis you'll be fucked.

Cash here refers to physical currency. It's not mandating that you take a loan for large purchases if that's what you're thinking.

It doesn't. You can still buy a house, or a car, just not with cash.