Indeed, KYC is a requirement that is applied by casino sites for each user, especially for users who will make withdrawal transactions with relatively large amounts.
However, as gamblers, we shouldn't need to feel disturbed and be concerned about the obligation of every user to do KYC.
Because the existence of KYC requested by the casino site has a good purpose in terms of security from the casino site and security for every account registered on the site.
Now all licenced casinos have KYC. The passing KYC is obligatory. But the most important thing is that users must be sure that their personal data are kept in a safe place because hackers hack non only money of users but personal data too and nobody knows how they will use this personal data.