If it's worth claiming (either fund wise or spite wise) have you checked to see if you can file a tax return and if they'll accept one. From what I've read about proof of earnings for the UK, it looks like the second most document that's used for things like this (the first being letters of proof from a person's employer).
Who said he is from UK ?
Also for UK residents they cannot open account at Stake.com. they can open at another domain stake.co.uk with different regulations.
However Stake became more strict since the owners made tons of money now all they care about is the legal
Part and the regulations . Aslo since they added the Fiat for deposit or withdrawals Stake is no more a crypto casino its just a casino that accept crypto
I'm afraid to think you're a little bit too naive IMO. If it was just a matter of regulation, ramanlop0 would have not been allowed to deposit his money there and to gamble it until reaching the platinum 4 rank that requires $2,500,000 to be wagered according to this page
https://help.stake.com/en/articles/4793501-stake-vip-program-overviewThe bear market has hit many crypto companies, Stake could be one of them and could encounter difficulties to pay out customers winnings now.