If you are doing something shady like parking your coins at their website and trying to withdraw without betting, then you will be at their radar to show who you are and what are you dealing with. For that, they may also ask you for online copies of your utility bill, passport, election ID, your SSN number, tax return slip and ID, etc. They will try their best to get their hands on you if they find you to be involved in any criminal or money laundering activities.