Just a thought - if you tell - say - bet365 to delete all your data under the GDPR rules and then open another account if it is gubbed from the start then surely they haven't deleted all your data and you can get them fined?
Cant they keep your details for 5 years or something with inactive/closed accounts ? I have no accounts left so I just straight up gamble these days in the bookies and its a lot less time consuming or stressful. Annoying though cos dont get the free bet with one loss on my accas (which happens quite a lot and thanks Brentford this week )