Since, when are casinos or other services asking for income proof from your Bitcoin or crypto wallet? I have never heard or experienced this before. When you are completing KYC verification whether it is for a casino, an exchange, or any other service online, they usually ask for your bank statements and other stuff like that so that they can see if you are actually earning money or not. Creating incoming and outgoing transactions in a blockchain wallet is very easy and anyone can bypass the verification if they are asking for such requirements now.

If you haven't been specifically asked for this and you are just assuming and asking from your side because they asked for proof of income, then I'm pretty sure they are not going to accept a pdf file of your electrum wallet showing your transactions because I don't think that can serve as a proof of income for a KYC verification.