It is good that you mention it, in reality rakeback manifests itself in different ways in casinos, particularly "chips" makes a lot of noise with the vault issue, I have not been involved with their system either, but more by disposition of time than of interest, but it is interesting to know that instead of having stagnant profits in a casino wallet, they can be had by winning "something" in the vault.
By the way, good that $ 100k promotion. + $2k BTT.
I think this could not be considered as a rakeback if you ask me. Rakeback is when you gamble and reach a certain level you get rakeback from all the losses you make, and that's about it there is nothing extra to it and that's why it's a simple thing.
Here however dividends are different, you could gamble for a month daily and get a lot of chips and you could just lock that all the time and all your earnings could be replayed and basically compounded so you could eventually get a lot of profit from this without gambling after a while, you can't get rakeback without gambling, but you could get dividends without gambling if you lock it and just collect it. That's what I think is going on here, that's what I believe is the difference between what rakeback is and what dividends are. Think about dividends as you own part of the company whereas rakeback as a promotion for being a customer.