On the other hand, today I have reached Queen level and Duelbits give me a nice reward that ready to claim.
Yeah, that level is quite difficult to reach for small bettors like me, but they give something decent as a reward
I got a Level up bonus of around $900

Congrats with leveling up! I don't consider you as a small gambler if you are able to wager over 500,000$

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That is very, very generous.
Is this reward fixed for every single person or is it variable (randomly generated)?
I don't know of any other casino that would offer this sort of bonus as a reward for loyalty to this platform. Congratulations on your status upgrade and hope you are able to unlock the rest of them too!
I think it is a fixed bonus. Most other casinos that have a vip system give some sort of bonus when leveling up; it keeps the players motivated trying to reaching a higher vip status.